Leviticus 6:10-11

6:10 Then the priest must put on his linen robe and must put linen leggings over his bare flesh, and he must take up the fatty ashes of the burnt offering that the fire consumed on the altar, and he must place them beside the altar. 6:11 Then he must take off his clothes and put on other clothes, and he must bring the fatty ashes outside the camp to a ceremonially clean place,