Leviticus 5:10-12 New International Version - UK (NIVUK)
10 The priest shall then offer the other as a burnt offering in the prescribed way and make atonement for them for the sin they have committed, and they will be forgiven.
11 ‘“If, however, they cannot afford two doves or two young pigeons, they are to bring as an offering for their sin a tenth of an ephah[a] of the finest flour for a sin offering. They must not put olive oil or incense on it, because it is a sin offering. 12 They are to bring it to the priest, who shall take a handful of it as a memorial[b] portion and burn it on the altar on top of the food offerings presented to the Lord. It is a sin offering.