Leviticus 5:8-10

5:8 He must bring them to the priest and present first the one that is for a sin offering. The priest must pinch its head at the nape of its neck, but must not sever the head from the body. 5:9 Then he must sprinkle some of the blood of the sin offering on the wall of the altar, and the remainder of the blood must be squeezed out at the base of the altar – it is a sin offering. 5:10 The second bird he must make a burnt offering according to the standard regulation. So the priest will make atonement on behalf of this person for his sin which he has committed, and he will be forgiven.