Leviticus 5:9-11 New Revised Standard Version (NRSV)
9 He shall sprinkle some of the blood of the sin offering on the side of the altar, while the rest of the blood shall be drained out at the base of the altar; it is a sin offering. 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.