Leviticus 6:9-10

9“Command Aaron and his sons that this is the law of the burnt offering: The burnt offering is to remain on the hearth of the altar all night, until morning, and the fire must be kept burning on the altar.

10And the priest shall put on his linen robe and linen undergarments, and he shall remove from the altar the ashes of the burnt offering that the fire has consumed and place them beside it.