Chanukah is discussed very little in the Mishnah or Gemara. Many often ask, “Why is Chanukah mentioned so briefly throughout the Gemara when there is a whole Masechta on Purim?” To answer this question, we must first explain an issue with the Gemara.
The Gemara starts its discussion of Chanukah by asking simply, “What is Chanukah?” As Rashi explains, it is wondering what miracle we celebrate on Chanukah, and why it was originally established. But why would the Gemara ask that question at all? It is certainly not the typical kind of question the Gemara raises! The Gemara raises this question because in the times of the Amoraim, the fundamentals of Chanukah were not clear. Why were the fundamental issues pertaining to Chanukah’s origins so uncertain during the Amoraic period? One possible explanation is that Rabi Yehuda HaNassi (who authored the Mishnah) was a descendant of David (see Shabbat 56a), and we know that after the Chashmonaim defeated the Syrian-Greeks, they took the kingship over Am Yisrael, which was supposed to stay within the family of David. Since the Chashmonaim assuming the role of king was wrong (as the Ramban states in his commentary to Breishit 49:10), Rabi Yehuda HaNassi did not emphasize it, so the details regarding the Chanukah story were not so well-known during the time of the Amoraim. It is possible that because of these reasons, Chanukah does not appear often in the Mishnah or Gemara.
Another suggested answer for our original question is that even though the fundamentals were clear and Chanukah was adequately stressed, the Mishnah was written very close to Churban Bayit Sheni. Therefore, people still felt the trauma of the destruction, so they did not want to write very much about it. Not wanting to sadden people, the authors of the Mishnah and Gemara did not deal with Chanukah at length. Perhaps they also did want a repeat of the Bar Kochva rebellion at that time, which modeled itself after the Chashmonaim’s miraculous victory against the Syrian-Greeks.
Even though the Gemara devotes relatively little attention to discussing the laws of Chanukah, the Rambam did stress them in his Mishnah Torah. He writes that whoever is obligated in the law of hearing the Megillah is obligated to light Chanukah candles. He also states that Chanukah is an opportunity to praise God, and in fact one is required to sell the clothes off his back to make sure he has enough oil for the eight days. This sounds like an extreme statement, but the Maggid Mishnah explains that the Rambam gets this idea from Pesach. One must sell his clothing to make sure he has enough for the four cups of wine on Pesach. The Rambam believes that just as one must go to the extreme for that Pirsumei Nissa, so, too, one must to do so for the Pirsumei Nissa of Chanukah. Thus, even though it is hardly mentioned in the Gemara, Chanukah is an extremely important holiday. It demonstrates our praise to God, and must not be neglected! Thus we are indebted to the Rambam for restoring Chanukah to its original glorious luster.