Leviticus 5:18
"And he shall bring a ram without blemish out of the flock, with thy estimation, for a trespass offering, unto the priest: and the priest shall make an atonement for him concerning his ignorance wherein he erred and wist it not, and it shall be forgiven him."
Cross References (ranked by relevance)
Leviticus 1:4
And he shall put his hand upon the head of the burnt offering; and it shall be accepted for him to make atonement for him.
Leviticus 4:20
And he shall do with the bullock as he did with the bullock for a sin offering, so shall he do with this: and the priest shall make an atonement for them, and it shall be forgiven them.