Let's set the scene.
Moses and the Israelites near the end of their journey through the desert. They're pretty much out of the desert proper and finally encountering tribes, kingdoms, and the brutal armies that go with them. They are now east of the Jordan river, heading northwest and headlong into a number of pagan kingdoms.
The first two kingdoms they must pass through are run by King Sichon, ruler of the Amorites, and King Og, ruler of the Bashan area. And right off the bat, the Israelites ask Sichon for permission to pass through his jurisdiction, promising not to go off the highway or attack anyone or steal anything.
Sichon's not buying it.
(כא) וַיִּשְׁלַ֤ח יִשְׂרָאֵל֙ מַלְאָכִ֔ים אֶל־סִיחֹ֥ן מֶֽלֶךְ־הָאֱמֹרִ֖י לֵאמֹֽר׃ (כב) אֶעְבְּרָ֣ה בְאַרְצֶ֗ךָ לֹ֤א נִטֶּה֙ בְּשָׂדֶ֣ה וּבְכֶ֔רֶם לֹ֥א נִשְׁתֶּ֖ה מֵ֣י בְאֵ֑ר בְּדֶ֤רֶךְ הַמֶּ֙לֶךְ֙ נֵלֵ֔ךְ עַ֥ד אֲשֶֽׁר־נַעֲבֹ֖ר גְּבֻלֶֽךָ׃ (כג) וְלֹא־נָתַ֨ן סִיחֹ֣ן אֶת־יִשְׂרָאֵל֮ עֲבֹ֣ר בִּגְבֻלוֹ֒ וַיֶּאֱסֹ֨ף סִיחֹ֜ן אֶת־כׇּל־עַמּ֗וֹ וַיֵּצֵ֞א לִקְרַ֤את יִשְׂרָאֵל֙ הַמִּדְבָּ֔רָה וַיָּבֹ֖א יָ֑הְצָה וַיִּלָּ֖חֶם בְּיִשְׂרָאֵֽל׃ (כד) וַיַּכֵּ֥הוּ יִשְׂרָאֵ֖ל לְפִי־חָ֑רֶב וַיִּירַ֨שׁ אֶת־אַרְצ֜וֹ....
(לג) וַיִּפְנוּ֙ וַֽיַּעֲל֔וּ דֶּ֖רֶךְ הַבָּשָׁ֑ן וַיֵּצֵ֣א עוֹג֩ מֶֽלֶךְ־הַבָּשָׁ֨ן לִקְרָאתָ֜ם ה֧וּא וְכׇל־עַמּ֛וֹ לַמִּלְחָמָ֖ה אֶדְרֶֽעִי׃
(לד) וַיֹּ֨אמֶר יְהֹוָ֤ה אֶל־מֹשֶׁה֙ אַל־תִּירָ֣א אֹת֔וֹ כִּ֣י בְיָדְךָ֞ נָתַ֧תִּי אֹת֛וֹ וְאֶת־כׇּל־עַמּ֖וֹ וְאֶת־אַרְצ֑וֹ וְעָשִׂ֣יתָ לּ֔וֹ כַּאֲשֶׁ֣ר עָשִׂ֗יתָ לְסִיחֹן֙ מֶ֣לֶךְ הָֽאֱמֹרִ֔י אֲשֶׁ֥ר יוֹשֵׁ֖ב בְּחֶשְׁבּֽוֹן׃ (לה) וַיַּכּ֨וּ אֹת֤וֹ וְאֶת־בָּנָיו֙ וְאֶת־כׇּל־עַמּ֔וֹ עַד־בִּלְתִּ֥י הִשְׁאִֽיר־ל֖וֹ שָׂרִ֑יד וַיִּֽירְשׁ֖וּ אֶת־אַרְצֽוֹ׃
(21) Israel now sent messengers to Sihon king of the Amorites, saying, (22) “Let me pass through your country. We will not turn off into fields or vineyards, and we will not drink water from wells. We will follow the king’s highway until we have crossed your territory.” (23) But Sihon would not let Israel pass through his territory. Sihon gathered all his people and went out against Israel in the wilderness. He came to Jahaz and engaged Israel in battle. (24) But Israel put them to the sword, and took possession of their land....
(33) They marched on and went up the road to Bashan, and King Og of Bashan, with all his people, came out to Edrei to engage them in battle.
(34) But the LORD said to Moses, “Do not fear him, for I give him and all his people and his land into your hand. You shall do to him as you did to Sihon king of the Amorites who dwelt in Heshbon.” (35) They defeated him and his sons and all his people, until no remnant was left him; and they took possession of his country.
So, why was Moses afraid of Og? Well, let's hear Moses' version of what happened.
(א) וַנֵּ֣פֶן וַנַּ֔עַל דֶּ֖רֶךְ הַבָּשָׁ֑ן וַיֵּצֵ֣א עוֹג֩ מֶֽלֶךְ־הַבָּשָׁ֨ן לִקְרָאתֵ֜נוּ ה֧וּא וְכׇל־עַמּ֛וֹ לַמִּלְחָמָ֖ה אֶדְרֶֽעִי׃ (ב) וַיֹּ֨אמֶר יְהֹוָ֤ה אֵלַי֙ אַל־תִּירָ֣א אֹת֔וֹ כִּ֣י בְיָדְךָ֞ נָתַ֧תִּי אֹת֛וֹ וְאֶת־כׇּל־עַמּ֖וֹ וְאֶת־אַרְצ֑וֹ וְעָשִׂ֣יתָ לּ֔וֹ כַּאֲשֶׁ֣ר עָשִׂ֗יתָ לְסִיחֹן֙ מֶ֣לֶךְ הָֽאֱמֹרִ֔י אֲשֶׁ֥ר יוֹשֵׁ֖ב בְּחֶשְׁבּֽוֹן׃ (ג) וַיִּתֵּן֩ יְהֹוָ֨ה אֱלֹהֵ֜ינוּ בְּיָדֵ֗נוּ גַּ֛ם אֶת־ע֥וֹג מֶֽלֶךְ־הַבָּשָׁ֖ן וְאֶת־כׇּל־עַמּ֑וֹ וַנַּכֵּ֕הוּ עַד־בִּלְתִּ֥י הִשְׁאִֽיר־ל֖וֹ שָׂרִֽיד׃ (ד) וַנִּלְכֹּ֤ד אֶת־כׇּל־עָרָיו֙ בָּעֵ֣ת הַהִ֔וא לֹ֤א הָֽיְתָה֙ קִרְיָ֔ה אֲשֶׁ֥ר לֹא־לָקַ֖חְנוּ מֵֽאִתָּ֑ם שִׁשִּׁ֥ים עִיר֙ כׇּל־חֶ֣בֶל אַרְגֹּ֔ב מַמְלֶ֥כֶת ע֖וֹג בַּבָּשָֽׁן׃
(יא) כִּ֣י רַק־ע֞וֹג מֶ֣לֶךְ הַבָּשָׁ֗ן נִשְׁאַר֮ מִיֶּ֣תֶר הָרְפָאִים֒ הִנֵּ֤ה עַרְשׂוֹ֙ עֶ֣רֶשׂ בַּרְזֶ֔ל הֲלֹ֣ה הִ֔וא בְּרַבַּ֖ת בְּנֵ֣י עַמּ֑וֹן תֵּ֧שַׁע אַמּ֣וֹת אׇרְכָּ֗הּ וְאַרְבַּ֥ע אַמּ֛וֹת רׇחְבָּ֖הּ בְּאַמַּת־אִֽישׁ׃
(1) We made our way up the road toward Bashan, and King Og of Bashan with all his men took the field against us at Edrei. (2) But the LORD said to me: Do not fear him, for I am delivering him and all his men and his country into your power, and you will do to him as you did to Sihon king of the Amorites, who lived in Heshbon. (3) So the LORD our God also delivered into our power King Og of Bashan, with all his men, and we dealt them such a blow that no survivor was left. (4) At that time we captured all his towns; there was not a town that we did not take from them: sixty towns, the whole district of Argob, the kingdom of Og in Bashan....
(11) Only King Og of Bashan was left of the remaining Rephaim. His bedstead, an iron bedstead, is now in Rabbah of the Ammonites; it is nine cubits long and four cubits wide, by the standard cubit!
Again, if a cubit were 1 1/2 feet, then Og's iron bed was 13 1/2 feet x 6 feet. He's a giant! Of course Moses would fear him!
Unless of course...we have proof that contradicts this notion.
Detour: let's go for a moment to the construction and dedication of the Tabernacle in the desert. The Tabernacle was like a huge rectangular tent, like a sukkah but with a cloth covering on top. It housed the menorah, incense altar, some other holy relics, and the Ark of the Covenant in the back room.
First, we read descriptions of some of the materials used for the frame of the tent, again using the formula 1 cubit = 1 1/2 feet.
(כ) וַיַּ֥עַשׂ אֶת־הַקְּרָשִׁ֖ים לַמִּשְׁכָּ֑ן עֲצֵ֥י שִׁטִּ֖ים עֹמְדִֽים׃ (כא) עֶ֥שֶׂר אַמֹּ֖ת אֹ֣רֶךְ הַקָּ֑רֶשׁ וְאַמָּה֙ וַחֲצִ֣י הָֽאַמָּ֔ה רֹ֖חַב הַקֶּ֥רֶשׁ הָאֶחָֽד׃
(20) They made the planks for the Tabernacle of acacia wood, upright. (21) The length of each plank was ten cubits, the width of each plank a cubit and a half.
Doing the math, that means each plank was 15 feet tall, not to mention just over 2 feet wide.
But wait...there's more.
(9) The length of each cloth [for covering the entire structure] was twenty-eight cubits, and the width of each cloth was four cubits, all cloths having the same measurements. (10) They joined five of the cloths to one another, and they joined the other five cloths to one another.
So the tapestry covering the Tabernacle was made of 2 gigantic pieces of cloth. Each was 28 cubits long and 20 cubits wide. That's 42 feet long by 30 feet wide...which were laid out on top of the structure, then hooked together up the middle by the loops sewn into them.
Now we read the story of the day the Tabernacle was dedicated...
(יז) וַיְהִ֞י בַּחֹ֧דֶשׁ הָרִאשׁ֛וֹן בַּשָּׁנָ֥ה הַשֵּׁנִ֖ית בְּאֶחָ֣ד לַחֹ֑דֶשׁ הוּקַ֖ם הַמִּשְׁכָּֽן׃ (יח) וַיָּ֨קֶם מֹשֶׁ֜ה אֶת־הַמִּשְׁכָּ֗ן וַיִּתֵּן֙ אֶת־אֲדָנָ֔יו וַיָּ֙שֶׂם֙ אֶת־קְרָשָׁ֔יו וַיִּתֵּ֖ן אֶת־בְּרִיחָ֑יו וַיָּ֖קֶם אֶת־עַמּוּדָֽיו׃ (יט) וַיִּפְרֹ֤שׂ אֶת־הָאֹ֙הֶל֙ עַל־הַמִּשְׁכָּ֔ן וַיָּ֜שֶׂם אֶת־מִכְסֵ֥ה הָאֹ֛הֶל עָלָ֖יו מִלְמָ֑עְלָה כַּאֲשֶׁ֛ר צִוָּ֥ה יְהֹוָ֖ה אֶת־מֹשֶֽׁה׃ {ס}
(17) In the first month of the second year, on the first of the month, the Tabernacle was set up. (18) Moses set up the Tabernacle, placing its sockets, setting up its planks, inserting its bars, and erecting its posts. (19) He spread the tent over the Tabernacle, placing the covering of the tent on top of it—just as the LORD had commanded Moses.
So Moses set the whole thing up himself. But how could one person erect multiple planks 15 feet high, then throw a 30 foot long tapestry over the top? How else...
אָמַר רַבִּי יוֹחָנָן אֵין הַקָּדוֹשׁ בָּרוּךְ הוּא מַשְׁרֶה שְׁכִינָתוֹ אֶלָּא עַל גִּבּוֹר וְעָשִׁיר וְחָכָם וְעָנָיו וְכוּלָּן מִמֹּשֶׁה גִּבּוֹר דִּכְתִיב וַיִּפְרֹשׂ אֶת הָאֹהֶל עַל הַמִּשְׁכָּן וְאָמַר מָר מֹשֶׁה רַבֵּינוּ פְּרָסוֹ וּכְתִיב עֶשֶׂר אַמּוֹת אֹרֶךְ הַקָּרֶשׁ וְגוֹ׳...
Rabbi Yoḥanan said: The Holy One, Blessed be He, rests His Divine Presence only upon one who is mighty, and wealthy, and wise, and humble. And all of these qualities are derived from Moses. He was mighty, as it is written: “And he spread the tent over the Tabernacle” (Exodus 40:19), and the Master said: Moses, our teacher, spread it himself. And it is written: “Ten cubits shall be the length of a board, and a cubit and a half the breadth of each board” (Exodus 26:16). Moses was tall and strong enough to spread the tent over the boards alone.
So we have an argument that, even if Og were a giant, Moses was pretty big himself. So then why did G-d tell Moses not to fear Og? If Moses wasn't afraid of Og's size, then there must've been something else.
For the answer, we take another DETOUR:
Here's a story from the time of Abraham known as the Wars of the Kings. In my experience, it's another story that most teachers gloss over and don't bother teaching, but for us, it's the key to unlocking the mystery of Og's power.
(א) וַיְהִ֗י בִּימֵי֙ אַמְרָפֶ֣ל מֶֽלֶךְ־שִׁנְעָ֔ר אַרְי֖וֹךְ מֶ֣לֶךְ אֶלָּסָ֑ר כְּדׇרְלָעֹ֙מֶר֙ מֶ֣לֶךְ עֵילָ֔ם וְתִדְעָ֖ל מֶ֥לֶךְ גּוֹיִֽם׃ (ב) עָשׂ֣וּ מִלְחָמָ֗ה אֶת־בֶּ֙רַע֙ מֶ֣לֶךְ סְדֹ֔ם וְאֶת־בִּרְשַׁ֖ע מֶ֣לֶךְ עֲמֹרָ֑ה שִׁנְאָ֣ב ׀ מֶ֣לֶךְ אַדְמָ֗ה וְשֶׁמְאֵ֙בֶר֙ מֶ֣לֶךְ צְבֹיִ֔ים וּמֶ֥לֶךְ בֶּ֖לַע הִיא־צֹֽעַר׃ (ג) כׇּל־אֵ֙לֶּה֙ חָֽבְר֔וּ אֶל־עֵ֖מֶק הַשִּׂדִּ֑ים ה֖וּא יָ֥ם הַמֶּֽלַח׃
(ד) שְׁתֵּ֤ים עֶשְׂרֵה֙ שָׁנָ֔ה עָבְד֖וּ אֶת־כְּדׇרְלָעֹ֑מֶר וּשְׁלֹשׁ־עֶשְׂרֵ֥ה שָׁנָ֖ה מָרָֽדוּ׃ (ה) וּבְאַרְבַּע֩ עֶשְׂרֵ֨ה שָׁנָ֜ה בָּ֣א כְדׇרְלָעֹ֗מֶר וְהַמְּלָכִים֙ אֲשֶׁ֣ר אִתּ֔וֹ וַיַּכּ֤וּ אֶת־רְפָאִים֙ בְּעַשְׁתְּרֹ֣ת קַרְנַ֔יִם וְאֶת־הַזּוּזִ֖ים בְּהָ֑ם וְאֵת֙ הָֽאֵימִ֔ים בְּשָׁוֵ֖ה קִרְיָתָֽיִם׃ (ו) וְאֶת־הַחֹרִ֖י בְּהַרְרָ֣ם שֵׂעִ֑יר עַ֚ד אֵ֣יל פָּארָ֔ן אֲשֶׁ֖ר עַל־הַמִּדְבָּֽר׃ (ז) וַ֠יָּשֻׁ֠בוּ וַיָּבֹ֜אוּ אֶל־עֵ֤ין מִשְׁפָּט֙ הִ֣וא קָדֵ֔שׁ וַיַּכּ֕וּ אֶֽת־כׇּל־שְׂדֵ֖ה הָעֲמָלֵקִ֑י וְגַם֙ אֶת־הָ֣אֱמֹרִ֔י הַיֹּשֵׁ֖ב בְּחַֽצְצֹ֥ן תָּמָֽר׃ (ח) וַיֵּצֵ֨א מֶֽלֶךְ־סְדֹ֜ם וּמֶ֣לֶךְ עֲמֹרָ֗ה וּמֶ֤לֶךְ אַדְמָה֙ וּמֶ֣לֶךְ צְבֹיִ֔ים וּמֶ֥לֶךְ בֶּ֖לַע הִוא־צֹ֑עַר וַיַּֽעַרְכ֤וּ אִתָּם֙ מִלְחָמָ֔ה בְּעֵ֖מֶק הַשִּׂדִּֽים׃ (ט) אֵ֣ת כְּדׇרְלָעֹ֜מֶר מֶ֣לֶךְ עֵילָ֗ם וְתִדְעָל֙ מֶ֣לֶךְ גּוֹיִ֔ם וְאַמְרָפֶל֙ מֶ֣לֶךְ שִׁנְעָ֔ר וְאַרְי֖וֹךְ מֶ֣לֶךְ אֶלָּסָ֑ר אַרְבָּעָ֥ה מְלָכִ֖ים אֶת־הַחֲמִשָּֽׁה׃
(י) וְעֵ֣מֶק הַשִּׂדִּ֗ים בֶּֽאֱרֹ֤ת בֶּאֱרֹת֙ חֵמָ֔ר וַיָּנֻ֛סוּ מֶֽלֶךְ־סְדֹ֥ם וַעֲמֹרָ֖ה וַיִּפְּלוּ־שָׁ֑מָּה וְהַנִּשְׁאָרִ֖ים הֶ֥רָה נָּֽסוּ׃ (יא) וַ֠יִּקְח֠וּ אֶת־כׇּל־רְכֻ֨שׁ סְדֹ֧ם וַעֲמֹרָ֛ה וְאֶת־כׇּל־אׇכְלָ֖ם וַיֵּלֵֽכוּ׃
(יב) וַיִּקְח֨וּ אֶת־ל֧וֹט וְאֶת־רְכֻשׁ֛וֹ בֶּן־אֲחִ֥י אַבְרָ֖ם וַיֵּלֵ֑כוּ וְה֥וּא יֹשֵׁ֖ב בִּסְדֹֽם׃ (יג) וַיָּבֹא֙ הַפָּלִ֔יט וַיַּגֵּ֖ד לְאַבְרָ֣ם הָעִבְרִ֑י וְהוּא֩ שֹׁכֵ֨ן בְּאֵֽלֹנֵ֜י מַמְרֵ֣א הָאֱמֹרִ֗י אֲחִ֤י אֶשְׁכֹּל֙ וַאֲחִ֣י עָנֵ֔ר וְהֵ֖ם בַּעֲלֵ֥י בְרִית־אַבְרָֽם׃ (יד) וַיִּשְׁמַ֣ע אַבְרָ֔ם כִּ֥י נִשְׁבָּ֖ה אָחִ֑יו וַיָּ֨רֶק אֶת־חֲנִיכָ֜יו יְלִידֵ֣י בֵית֗וֹ שְׁמֹנָ֤ה עָשָׂר֙ וּשְׁלֹ֣שׁ מֵא֔וֹת וַיִּרְדֹּ֖ף עַד־דָּֽן׃ (טו) וַיֵּחָלֵ֨ק עֲלֵיהֶ֧ם ׀ לַ֛יְלָה ה֥וּא וַעֲבָדָ֖יו וַיַּכֵּ֑ם וַֽיִּרְדְּפֵם֙ עַד־חוֹבָ֔ה אֲשֶׁ֥ר מִשְּׂמֹ֖אל לְדַמָּֽשֶׂק׃ (טז) וַיָּ֕שֶׁב אֵ֖ת כׇּל־הָרְכֻ֑שׁ וְגַם֩ אֶת־ל֨וֹט אָחִ֤יו וּרְכֻשׁוֹ֙ הֵשִׁ֔יב וְגַ֥ם אֶת־הַנָּשִׁ֖ים וְאֶת־הָעָֽם׃
(יז) וַיֵּצֵ֣א מֶֽלֶךְ־סְדֹם֮ לִקְרָאתוֹ֒ אַחֲרֵ֣י שׁוּב֗וֹ מֵֽהַכּוֹת֙ אֶת־כְּדׇרְלָעֹ֔מֶר וְאֶת־הַמְּלָכִ֖ים אֲשֶׁ֣ר אִתּ֑וֹ אֶל־עֵ֣מֶק שָׁוֵ֔ה ה֖וּא עֵ֥מֶק הַמֶּֽלֶךְ׃ (יח) וּמַלְכִּי־צֶ֙דֶק֙ מֶ֣לֶךְ שָׁלֵ֔ם הוֹצִ֖יא לֶ֣חֶם וָיָ֑יִן וְה֥וּא כֹהֵ֖ן לְאֵ֥ל עֶלְיֽוֹן׃ (יט) וַֽיְבָרְכֵ֖הוּ וַיֹּאמַ֑ר בָּר֤וּךְ אַבְרָם֙ לְאֵ֣ל עֶלְי֔וֹן קֹנֵ֖ה שָׁמַ֥יִם וָאָֽרֶץ׃ (כ) וּבָרוּךְ֙ אֵ֣ל עֶלְי֔וֹן אֲשֶׁר־מִגֵּ֥ן צָרֶ֖יךָ בְּיָדֶ֑ךָ וַיִּתֶּן־ל֥וֹ מַעֲשֵׂ֖ר מִכֹּֽל׃
(1) Now, when King Amraphel of Shinar, King Arioch of Ellasar, King Chedorlaomer of Elam, and King Tidal of Goiim (2) made war on King Bera of Sodom, King Birsha of Gomorrah, King Shinab of Admah, King Shemeber of Zeboiim, and the king of Bela, which is Zoar, (3) all the latter joined forces at the Valley of Siddim, now the Dead Sea.
(4) Twelve years they served Chedorlaomer, and in the thirteenth year they rebelled. (5) In the fourteenth year Chedorlaomer and the kings who were with him came and defeated the Rephaim at Ashteroth-karnaim, the Zuzim at Ham, the Emim at Shaveh-kiriathaim, (6) and the Horites in their hill country of Seir as far as El-paran, which is by the wilderness. (7) On their way back they came to En-mishpat, which is Kadesh, and subdued all the territory of the Amalekites, and also the Amorites who dwelt in Hazazon-tamar. (8) Then the king of Sodom, the king of Gomorrah, the king of Admah, the king of Zeboiim, and the king of Bela, which is Zoar, went forth and engaged them in battle in the Valley of Siddim: (9) King Chedorlaomer of Elam, King Tidal of Goiim, King Amraphel of Shinar, and King Arioch of Ellasar—four kings against those five.
(10) Now the Valley of Siddim was dotted with bitumen pits; and the kings of Sodom and Gomorrah, in their flight, threw themselves into them, while the rest escaped to the hill country. (11) [The invaders] seized all the wealth of Sodom and Gomorrah and all their provisions, and went their way.
(12) They also took Lot, the son of Abram’s brother, and his possessions, and departed; for he had settled in Sodom. (13) A fugitive brought the news to Abram the Hebrew, who was dwelling at the terebinths of Mamre the Amorite, kinsman of Eshkol and Aner, these being Abram’s allies. (14) When Abram heard that his kinsman had been taken captive, he mustered his retainers, born into his household, numbering three hundred and eighteen, and went in pursuit as far as Dan. (15) At night, he and his servants deployed against them and defeated them; and he pursued them as far as Hobah, which is north of Damascus. (16) He brought back all the possessions; he also brought back his kinsman Lot and his possessions, and the women and the rest of the people.
(17) When he returned from defeating Chedorlaomer and the kings with him, the king of Sodom came out to meet him in the Valley of Shaveh, which is the Valley of the King. (18) And King Melchizedek of Salem brought out bread and wine; he was a priest of God Most High. (19) He blessed him, saying, “Blessed be Abram of God Most High, Creator of heaven and earth. (20) And blessed be God Most High, Who has delivered your foes into your hand.” And [Abram] gave him a tenth of everything.
If Og was the last of the Rephaim, and this is the story wherein the Rephaim were wiped out, then this story would be telling us how Og escaped that fate. Therefore, we equate the unnamed "fugitive" with Og.
So why was Moses afraid to face Og if height wasn't an issue? It was because Og had been protected by G-d throughout his life as thanks for saving Lot, Abram's nephew.
Actually, Rashi was quoting the Talmud below.
ויאמר ה' אל משה אל תירא מכדי סיחון ועוג אחי הוו דאמר מר סיחון ועוג בני אחיה בר שמחזאי הוו מאי שנא מעוג דקמסתפי ומאי שנא מסיחון דלא קמסתפי א"ר יוחנן אר"ש בן יוחי מתשובתו של אותו צדיק אתה יודע מה היה בלבו אמר שמא תעמוד לו זכות של אברהם אבינו שנאמר (בראשית יד, יג) ויבא הפליט ויגד לאברם העברי
Before the battle against Og, king of Bashan, it is stated: “And the Lord said to Moses: Do not fear him; for I have delivered him into your hand, and all his people, and his land; and you shall do to him as you did to Sihon king of the Amorites, who dwelt at Heshbon” (Numbers 21:34). The Gemara asks: Now, Sihon and Og were brothers, as the Master said: Sihon and Og were sons of Ahijah, son of Shamhazai. In what way is Sihon different from Og, that God found it necessary to warn Moses not to be afraid of Og, and in what way is Og different from Sihon, that there was no need for a warning not to be afraid of Sihon? Rabbi Yoḥanan says that Rabbi Shimon ben Yoḥai says: From the answer that God gave to that righteous one, Moses, you know what was in his heart, i.e., what gave Moses cause to fear. Moses said to himself: Perhaps the merit of our forefather Abraham will stand for Og and save him. Og was the one who told Abraham that Lot had been taken captive by the four kings, enabling Abraham to rescue Lot. The Gemara cites the source of this claim. As it is stated: “And there came one that was saved, and told Abram the Hebrew, now he dwelt by the terebinths of Mamre the Amorite, brother of Eshkol, and brother of Aner; and these were confederate with Abram. And when Abram heard that his brother was taken captive, he led forth his trained men, born in his house, three hundred and eighteen, and pursued as far as Dan” (Genesis 14:13–14).
Now to be honest, Rashi says it's possible that, even if Og were the one to have saved Lot, his motive wasn't to get anyone freed but, rather, to trick Abram into going to a battle he was sure to lose, after which Og, now without a kingdom and the last of his kind, would marry Sarah and take over their household as the start of a new nation.
So now, back to our story. Og ran out to attack the Israelites, a final affront to G-d, who told Moses not to fear: Og will be delivered to them just like his cousin, Sichon. So here's what happened next.
אֲמַר מַחֲנֵה יִשְׂרָאֵל כַּמָּה הָוֵי — תְּלָתָא פַּרְסֵי, אֵיזֵיל וְאֶיעֱקַר טוּרָא בַּר תְּלָתָא פַּרְסֵי וְאִישְׁדֵּי עֲלַיְיהוּ, וְאִיקְטְלִינְהוּ.
אֲזַל עֲקַר טוּרָא בַּר תְּלָתָא פַּרְסֵי וְאַיְיתִי עַל רֵישֵׁיהּ, וְאַיְיתִי קוּדְשָׁא בְּרִיךְ הוּא עֲלֵיהּ קַמְצֵי וְנַקְבוּהּ, וּנְחֵית בְּצַוְּארֵיהּ. הֲוָה בָּעֵי לְמִשְׁלְפֵהּ, מָשְׁכִי שִׁינֵּיהּ לְהַאי גִּיסָא וּלְהַאי גִּיסָא וְלָא מָצֵי לְמִשְׁלְפֵהּ. וְהַיְינוּ דִּכְתִיב: ״שִׁנֵּי רְשָׁעִים שִׁבַּרְתָּ״. וְכִדְרַבִּי שִׁמְעוֹן בֶּן לָקִישׁ. דְּאָמַר רַבִּי שִׁמְעוֹן בֶּן לָקִישׁ: מַאי דִּכְתִיב ״שִׁנֵּי רְשָׁעִים שִׁבַּרְתָּ״ — אַל תִּקְרֵי ״שִׁבַּרְתָּ״ אֶלָּא ״שִׁרְבַּבְתָּ״.
מֹשֶׁה כַּמָּה הֲוָה — עֶשֶׂר אַמּוֹת, שְׁקֵיל נַרְגָּא בַּר עֲשַׂר אַמִּין, שְׁוַור עֲשַׂר אַמִּין, וּמַחְיֵיהּ בְּקַרְסוּלֵּיהּ וְקַטְלֵיהּ.
Og said: How large is the camp of Israel? It is three parasangs. I will go and uproot a mountain three parasangs long and I will hurl it upon them and kill them.
He went, uprooted a mountain three parasangs long, and brought it on his head. And The Holy One, Blessed be He, brought grasshoppers upon it and they pierced the peak of the mountain and it fell on his neck. Og wanted to remove it from his head; his teeth were extended to one side of his head and to the other and he was unable to remove it. And that is what is written: “You break the teeth of the wicked” (Psalms 3:8). And this is in accordance with the homiletic interpretation of Rabbi Shimon Ben Lakish, as Rabbi Shimon Ben Lakish said: What is the meaning of that which is written: “You break the teeth of the wicked”? Do not read it as: You break [shibarta], but rather as: You lengthened [shirbavta].
The story concludes: How tall was Moses? He was ten cubits tall. He took an axe ten cubits long, jumped up ten cubits, and struck Og in the ankle and killed him.
And with that note that Moses was 15 feet tall, Rashi mentions that we already knew Moses was tall because the Torah stated that he himself, he alone, erected the Tabernacle, which would've required Moses to be incredibly tall to do so. And so, we come full circle, and the opening legend now appears completely relevant to this story after all.