The sacrifice is always marked to be without blemish, thereby evidently pointing to him, who is a lamb without blemish and without spot. 1 Peter 1:19.
Leviticus 5:16-19
16 And he shall make amends for the harm that he hath done in the holy thing, and shall add the fifth part thereto, and give it unto the priest: and the priest shall make an atonement for him with the ram of the trespass offering, and it shall be forgiven him.
17 And if a soul sin, and commit any of these things which are forbidden to be done by the commandments of the LORD; though he wist it not, yet is he guilty, and shall bear his iniquity.
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.
19 It is a trespass offering: he hath certainly trespassed against the LORD.