Leviticus 5:7, 11

‘But if he cannot afford a lamb, then he shall bring two turtledoves or two young pigeons as his guilt offering for his sin to the LORD, one as a sin offering and the other as a burnt offering.

‘But if he cannot afford to bring two turtledoves or two young pigeons, then he shall bring as his offering for his sin the tenth part of an ephah of fine flour as a sin offering; he shall not put [olive] oil or incense on it, for it is a sin offering.