The miracles and laws of the days of Chanukah are not recorded in the Mishnayot or other Tannaic writings and we do not have a “Masechet Chanukah” as we do for (almost) all other Jewish holidays. We therefore do not find these laws delineated in the Mishnah (besides for certain minor references to Chanukah in Masechet Bikkurim about when Bikkurim are brought, in Masechet Rosh Hashanah regarding witnesses for sanctification of the New Moon, and in Masechet Baba Kama regarding Chanukah candles causing damage). Nevertheless, the primary place the Sages of the Talmud discussed this topic is in Masechet Shabbat (21b and on) where the Gemara discusses the laws of Chanukah and the essence of these days. Let us now quote the words of the Gemara:
“What is Chanukah? Our Sages taught: On the twenty-fifth of Kislev, the eight days of Chanukah begin during which it is forbidden to fast or eulogize. When the Assyrian-Greeks entered the sanctuary (of the Bet Hamikdash), they defiled all the oils in the sanctuary. When the Hashmonai family overcame them and were victorious, they found only one container of oil with the seal of the Kohen Gadol intact and it was only sufficient to light for one day. A miracle happened and it remained lit for eight days. The next year, these days were established and designated as holidays with praise and thanksgiving to Hashem.”
Thus, although many miracles occurred during that time, the primary Mitzvah during Chanukah is lighting the candles in commemoration of the miracle which took place with the flask of oil that remained lit for eight days until they could procure some new pure oil. This is why we light candles every night during the eight days of Chanukah.
Maran Ha’Bet Yosef (Chapter 670) questions why the Sages established Chanukah for eight days, for in truth, the oil was sufficient to last for one day and thus, the miracle only lasted seven days! If so, the holiday of Chanukah should only be celebrated for seven days!
Many great Acharonim write lengthily in their Derashot to answer the Bet Yosef’s question. Indeed, Maran Ha’Bet Yosef offers several answers himself:
Firstly, during each night of these eight nights, they did not pour the regular amount of oil into the Menorah. Rather, they only poured in an eighth of the amount they would usually pour in. Nevertheless, the candles remained lit for eight days. Thus, the miracle began from the first time they lit the Menorah, for this small amount of oil sufficed for the Menorah to remain lit all night long.
Secondly, from the first night when they filled up the Menorah, they saw that there was nothing missing from the jug. Thus, the miracle began from the first night.
The Acharonim question the Bet Yosef’s first answer and ask how it was that the Hashmonai family allowed themselves to fill the Menorah with only an eighth of the requisite amount, do we not have a rule that one may not rely on miracles? They should have filled it with the regular amount of oil!
Maran Rabbeinu Ovadia Yosef zt”l answers that since the Hashmonai family saw all of the tremendous miracles of the time in their military victory against the mighty Greeks, they realized that Heaven was not guiding them along a regular, natural path. Thus, they understood that these miracles would continue with regards to the lighting of the Menorah as well. It is for this reason that they decided to fill the Menorah with only an eighth of the amount of oil in the lone pure jug.
All of these things show how dear the Jewish nation is to Hashem. Thus, during the days of Chanukah when we praise Hashem for the miracles he performed for us so many years ago, we must likewise remember how beloved we are to Hashem and this is just as true in our generation when we enjoy Hashem’s divine protection as we dwell in a land surrounded by fierce enemies who wish to destroy us but Hashem continues to protect us!
Based on this, Maran zt”l derived (in his Derashot) that although one should not pray for a miracle, nevertheless, when praying for the entire Jewish nation, one may pray to Hashem that He act with us in a miraculous manner, for the very existence of the Jewish nation is supernatural. It is therefore permissible to pray for a miracle when praying for the entirety of the Jewish nation.