Leviticus 5:6-7

6He shall bring his guilt offering to the Lord for the sin which he has committed, a female from the flock, a lamb or a goat as a sin offering. So the priest shall make atonement on his behalf for his sin.

7‘But if he cannot afford a lamb, then he shall bring two turtledoves or two young pigeons as his guilt offering for his sin to the Lord, one as a sin offering and the other as a burnt offering.