Leviticus 5:8-9

CLV(i) 8 He will bring them to the priest who will bring near the one for the sin offering first. The priest will pinch off its head toward its nape yet shall not separate it. 9 He will spatter some of the blood of the sin offering against the sidewall of the altar; and the remainder of the blood shall be wrung out at the foundation of the altar; it is a sin offering.