Leviticus 5:6-7

⁶Then he must bring his guilt offering to Yahweh for the sin that he has committed, a female animal from the flock, either a lamb or a goat, for a sin offering, and the priest will make atonement for him concerning his sin.

⁷If he cannot afford to buy a lamb, then he can bring as his guilt offering for his sin two doves or two young pigeons to Yahweh, one for a sin offering and the other for a burnt offering.