Leviticus 5:6-7

6He must bring his penalty for guilt for the sin he has committed to the Lord: a female lamb or goat from the flock as a sin offering. In this way the priest will make atonement on his behalf for his sin.

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.