Leviticus 6:2-4

2“Command Aaron and his sons, saying: This is the Torah of the burnt offering. The burnt offering shall remain on the hearth atop the altar all night until the morning, while the fire of the altar is kept burning on it.

3The kohen is to put on his linen garment, with his linen undergarments on his body. He is to remove the fat ashes from where the fire has consumed the burnt offering on the altar and put them beside the altar.

4Then he is to take off his garments, put on other ones, and carry the ashes outside the camp to a clean place.