Leviticus 5:7-10

7“But if he cannot afford an animal from the flock, then he may bring to the Lord two turtledoves or two young pigeons as penalty for guilt for his sin — one as a sin offering and the other as a burnt offering.

8He is to bring them to the priest, who will first present the one for the sin offering. He is to twist its head at the back of the neck without severing it.

9Then he will sprinkle some of the blood of the sin offering on the side of the altar, while the rest of the blood is to be drained out at the base of the altar; it is a sin offering.

10He will prepare the second bird as a burnt offering according to the regulation. In this way the priest will make atonement on his behalf for the sin he has committed, and he will be forgiven.