Siman 683

On Chanukah we complete the Hallel, because on every day a miracle was performed with the cruse of oil. Furthermore: because every day is distinct in its candles, according to the mehadrin min hamehadrin, and it is like Sukkot which are distinct in their sacrifices and we complete the Hallel. Furthermore: for we read the section of the Nesi'im, and every day the Nasi of that day is distinct from that of his fellow. If so, every Nasi must complete the Hallel over his sacrifices (Beit Yosef). Furthermore: for according to what I wrote in siman 670, they established the eight days of Chanukah in place of the days of Sukkot, which they did not observe then. And automatically, we complete the Hallel as on the festival of Sukkot.

All eight days of Chanukah one does not say Tachanun, or "Tzidkatkha Tzedek," or "Ya'ankha," or Tzidduk HaDin. Similarly, in the Mincha of the eve of Chanukah one does not say Tachanun, as I have written in siman 131. And on these days it is forbidden to fast, as I have written in siman 670, and one increases somewhat in the meals, and one says songs and praises, as I have written there.