Leviticus 5:10-12 New Revised Standard Version (NRSV)
10 And the second he shall offer for a burnt offering according to the regulation. Thus the priest shall make atonement on your behalf for the sin that you have committed, and you shall be forgiven.
11 But if you cannot afford two turtledoves or two pigeons, you shall bring as your offering for the sin that you have committed one-tenth of an ephah of choice flour for a sin offering; you shall not put oil on it or lay frankincense on it, for it is a sin offering. 12 You shall bring it to the priest, and the priest shall scoop up a handful of it as its memorial portion, and turn this into smoke on the altar, with the offerings by fire to the Lord; it is a sin offering.