Guilt Offering is one of the sacrifices in the Old Testament era, offered to seek forgiveness from God when a crime has been committed. {{:5 Major Sacrifices}}
Lev 5:14The Lord spoke to Moses, saying,Lev 5:15“If anyone commits a breach of faith and sins unintentionally in any of the holy things of the Lord, he shall bring to the Lord as his guilt offering a ram without blemish out of the flock, estimated by you in shekels of silver, according to the shekel of the sanctuary, for a guilt offering.Lev 5:16He shall also make restitution for the wrong that he has done in the holy thing and add a fifth to it and give it to the priest. And the priest shall make atonement for him with the ram of the guilt offering, and he shall be forgiven.Lev 5:17“If anyone sins, doing any of the things that by the Lord’s commandments ought not to be done, though he did not know it, yet he has become guilty and shall bear his iniquity.Lev 5:18He shall bring to the priest a ram without blemish out of the flock, or its equivalent, for a guilt offering, and the priest shall make atonement for him concerning the error that he committed unintentionally, and he shall be forgiven.Lev 5:19It is a guilt offering; he has certainly committed a breach of faith against the Lord.”
Lev 6:2“If anyone sins and commits a breach of faith against the Lord by deceiving his neighbor in a matter of deposit or security, or through robbery, or if he has oppressed his neighborLev 6:3or has found something lost and lied about it, swearing falsely—in any of all the things that people do and sin thereby—Lev 6:4if he has sinned and has realized his guilt and will restore what he took by robbery or what he got by oppression or the deposit that was committed to him or the lost thing that he foundLev 6:5or anything about which he has sworn falsely, he shall restore it in full and add a fifth to it, and give it to him to whom it belongs on the day he realizes his guilt.Lev 6:6And he shall bring to the Lord as his guilt offering a ram without blemish out of the flock, or its equivalent, to the priest for a guilt offering.Lev 6:7And the priest shall make atonement for him before the Lord, and he shall be forgiven for any of the things that he may have done to incur guilt.”
It is offered when one sins against holy things, violates God's commandments, or causes damage to another person's property (see Lev 6:2), and an additional fifth is added to the amount of damage caused.
The reason for this is that it is a sacrifice with the nature of restitution.
A guilt offering was also made when one committed a sexual sin by violating a female servant.
Lev 19:20“If a man lies sexually with a woman who is a slave, assigned to another man and not yet ransomed or given her freedom, there shall be an inquiry. They shall not be put to death, because she was not free;Lev 19:21but he shall bring his guilt offering to the Lord, to the entrance of the tent of meeting, a ram for a guilt offering.Lev 19:22And the priest shall make atonement for him with the ram of the guilt offering before the Lord for the sin that he has committed, and the sin that he has committed shall be forgiven him.