Leviticus 6 v 1 And the LORD spake unto Moses, saying, 2 If a soul sin, and commit a trespass against the LORD, and lie unto his neighbour in that which was delivered him to keep, or in fellowship, or in a thing taken away by violence, or hath deceived his neighbour; 3 Or have found that which was lost, and lieth concerning it, and sweareth falsely; in any of all these that a man doeth, sinning therein: 4 Then it shall be, because he hath sinned, and is guilty, that he shall restore that which he took violently away, or the thing which he hath deceitfully gotten, or that which was delivered him to keep, or the lost thing which he found, 5 Or all that about which he hath sworn falsely; he shall even restore it in the principal, and shall add the fifth part more thereto, and give it unto him to whom it appertaineth, in the day of his trespass offering. 6 And he shall bring his trespass offering unto the LORD, a ram without blemish out of the flock, with thy estimation, for a trespass offering, unto the priest: 7 And the priest shall make an atonement for him before the LORD: and it shall be forgiven him for any thing of all that he hath done in trespassing therein.
The offerer has repented of his sin. He has confessed his sin by going in to the temple and confessing his sin to the priest. He has paid restitution to the victim and added a fifth to it to make good the loss.
All this is not enough for him to be declared forgiven. He must also sacrifice a ram without blemish. The innocent must suffer death for the guilty. This typifies our Saviour the Lord Jesus Christ dying on calvary.