Confession of sin is addressed in 1 John, in the Epistle of James, and in Proverbs 28.
In 1 John 1:9:
9 If we confess our sins, he is faithful and just to forgive us our sins, and to cleanse us from all unrighteousness.
In James 5:16:
16 Confess your faults one to another, and pray one for another, that ye may be healed. The effectual fervent prayer of a righteous man availeth much.
In Proverbs 28:13:
13 He that covereth his sins shall not prosper: but whoso confesseth and forsaketh them shall have mercy.