Leviticus 4:13-14

13"If the whole congregation of Israel sins unintentionally and the thing is hidden from the eyes of the assembly, and they do any one of the things that by the Lord's commandments ought not to be done, and they realize their guilt,

14when the sin which they have committed becomes known, the assembly shall offer a bull from the herd for a sin offering and bring it in front of the tent of meeting.