"What is Chanukah? On the 25th of Kislev..." (Shabbat 21b)

Why did the miracle of Chanukah take place on the 25th of Kislev?

ANSWER:

In the desert, the construction of the Mishkan was completed on the 25th of Kislev (Yalkut Shimoni, 1 Kings 184). Hashem told Moshe to wait with the dedication till the auspicious day of Rosh Chodesh Nissan. The 25th of Kislev was somewhat offended, and to appease her, the rededication of the second Beit Hamikdash, in the days of the Hasmoneans, took place on the 25th of Kislev.

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It is interesting to note that the words in Bamidbar 7:84 "this is the dedication of the Mizbeach" which refer to the Mishkan (and are part of the Torah reading for Chanukah), have the numerical value of 954, which is the exact numerical value of "this (dedication) will be in the days of the Hasmoneans."