Leviticus 5:7-8

7‘But if 1he 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, 2one for a sin offering and the other for a burnt offering.

8He shall bring them to the priest, who shall offer first that which is for the sin offering and shall nip its head at the front of its neck, but he 3shall not sever it.