מתני׳ קראו את המגילה באדר הראשון ונתעברה השנה קורין אותה באדר שני אין בין אדר הראשון לאדר השני אלא קריאת המגילה ומתנות לאביונים: גמ׳רבי אליעזר ברבי יוסי סבר בכל שנה ושנה מה כל שנה ושנה אדר הסמוך לשבט אף כאן אדר הסמוך לשבט ורשר"ג סבר בכל שנה ושנה מה כל שנה ושנה אדר הסמוך לניסן אף כאן אדר הסמוך לניסן בשלמא רבי אליעזר ברבי יוסי מסתבר טעמא דאין מעבירין על המצות אלא רשב"ג מ"ט אמר רבי טבי טעמא דרבי שמעון בן גמליאל מסמך גאולה לגאולה עדיף
. If they read the Megillah during the first Adar and the year was intercalated (a month was added), it is read again in the second Adar. There is no difference between the first Adar and the second Adar except the reading of the Megillah and the giving of gifts to the poor. GEMARA. R. Eliezer son of Yose reasoned: “In every year”; just as in most years Adar is next to Shevat, so too here Adar is next to Shevat. R. Shimon b. Gamaliel reasoned: “In every year”; just as in most years Adar is next to Nisan, so to here Adar is next to Nisan. R. Eliezer, who holds that Purim is observed in Adar I makes sense for there is a principle that one should never pass up an opportunity to perform a mitzvah. But why would R. Shimon b. Gamaliel hold that Purim is delayed until Adar II. R. Tabi says that R. Shimon b. Gamaliel wanted the redemption of Purim to be close to the redemption of Pesah. Therefore, they should be observed in adjacent months.
R. Eliezer, who holds that Purim is observed in Adar I makes sense for there is a principle that one should never pass up an opportunity to perform a mitzvah. But why would R. Shimon b. Gamaliel hold that Purim is delayed until Adar II.
R. Tabi says that R. Shimon b. Gamaliel wanted the redemption of Purim to be close to the redemption of Pesah. Therefore, they should be observed in adjacent months.
Why didn't the Gemara ask "zerizim makdimin leMitzvos"?