The first part of the daily service in the Beis HaMidash (Holy Temple) was to take out the ashes from upon the altar. Naturally, all the Kohanim (Priests) wanted to perform this service. So many of them woke up early in the morning, before the call of the rooster, to immerse in the Mikvah (ritual bath) and prepare to perform this service. Originally, it was done on a first-come-first-serve basis, basically having all the Kohanim race up the ramp of the Copper Altar and the first to get there cleaned out the ashes. However, one time, a Kohen in his zealousness to perform this service mistakenly pushed another competing Kohen during the race, and the latter broke his leg. Therefore, the Rabbis instituted that there should be a daily lottery/raffle to decide who should perform this service. A certain Kohen was in charge of deciding who would be the one to perform this service. The Mishnah says (Tamid 26a),
"The appointed Kohen would arrive, but not at the same time every day. Sometimes he would come with the crowing of the rooster, or near that time before or after it. He would come and knock on the door [to the Chamber of the Fire where the Kohanim slept]. They [the Kohanim] would open the door. He [the appointed one] would day to them, 'All those who [already] immersed, draw for the lottery.' They drew a lottery and who ever won, won [the privilege to perform the ashes service]."Where would this lottery take place? All of the other lotteries in the Holy Temple took place in the Chamber of Hewn Stone, where the Sanhedrin sat. However, explain Rashi and Rabbi Asher ben Yechiel (1250-1328), this lottery took place in the Chamber of Fire, where Kohanim slept because the rest of the Holy Temple was still locked from the night, and it was more convenient. However, the Maimonides writes (Laws of Daily and Extra Sacrificial Offerings, 4:1) that even this lottery was drawn in the Chamber of Hewn Stone like all other lotteries in the Holy Temple.