Leviticus 5:7; Leviticus 5:11

7 'But if he cannot afford a lamb, then he shall bring to the LORD his guilt offering for that in which he has sinned, two turtledoves or two young pigeons, one for a sin offering and the other for a burnt offering.

11 'But if his means are insufficient for two turtledoves or two young pigeons, then for his offering for that which he has sinned, he shall bring the tenth of an ephah of fine flour for a sin offering; he shall not put oil on it or place incense on it, for it is a sin offering.