Musar zu Schemuel II 24:26

Spelling out what one has done wrong reveals one's inner thoughts, and makes it less likely that such a sin would be committed again. It reveals one's belief that G–d is aware of all his deeds. Having admitted that one had been foolish in sinning and resolving not to do so again, helps to secure G–d's goodwill. G–d, after all, is most interested in the welfare of His creatures. So far the Sefer Hachinuch.