בשפתים. וְלֹא בַּלֵּב (שם): בשפתים [OR IF A SOUL SWEAR, PRONOUNCING] WITH HIS LIPS [FOR HARM, OR FOR GOOD] — with his lips but not merely in his heart (Sifra, Vayikra Dibbura d'Chovah, Section 9 2; Shevuot 26b).
להרע. לְעַצְמוֹ: להרע TO DO HARM to himself,
או להיטיב. לְעַצְמוֹ, כְּגוֹן אֹכַל וְלֹא אֹכַל, אִישַׁן וְלֹא אִישַׁן (שבועות כ"ז): או להטיב OR TO DO GOOD to himself, — as for instance, if he swears: “I shall eat” (which is להטיב), or, “I shall not eat” (להרע), “I shall sleep” (להטיב) or, “I shall not sleep” (להרע) (cf. Shevuot 27a).
לכל אשר יבטא. לְרַבּוֹת לְשֶׁעָבַר: לכל אשר יבטא WHATSOEVER IT BE THAT A MAN PRONOUNCETH [WITH AN OATH] whatsoever it be: — this is intended to include the case where the oath refers to something that happened in the past (e.g., he swore, “I have eaten” etc. but he has not) (Sifra, Vayikra Dibbura d'Chovah, Section 9 8; Shevuot 26a).
ונעלם ממנו. וְעָבַר עַל שְׁבוּעָתוֹ, כָּל אֵלֶּה בְּקָרְבָּן עוֹלֶה וְיוֹרֵד, כַּמְּפֹרָשׁ כָּאן, אֲבָל שְׁבוּעָה שֶׁיֵּשׁ בָּהּ כְּפִירַת מָמוֹן אֵינָהּ בְּקָרְבָּן זוֹ אֶלָּא בְּאָשָׁם: ונעלם ממנו AND IT BE HID FROM HIM (he forgot that he had taken such an oath) and consequently he violated his oath. — All these cases come under the law of “a sacrifice of higher or lesser value” (according to pecuniary conditions), as is set forth here (vv. 6—13): but an oath which involves the false repudiation of a claim to money does not come under the law of this sacrifice but under that of a guilt-offering (v. 25).