Confession of sins is of utmost importance. “G‑d then reviewed the laws of theft, in order to encourage the Jewish people to make sure they were not in any way guilty of this sin before setting out on their journey toward the Land of Israel.
[G‑d instructed Moses to tell the Jewish people,] “When a man or woman sins, and feels guilty and confesses the sin he [or she] committed.” Numbers 5:6-7
If we have wronged a fellow human being in some way, we must first ask their forgiveness; then, we must restore the item or pay for any damage we caused. Then, we must “apologize” to G‑d, through repentance. Repentance consists of three steps:
regret for the past,
positive resolution for the future, and
verbal confession to G‑d of the misdeed.
Every misdeed creates negative energy, which has a “body” and a “soul.” The “body” of this energy is the misdeed itself, while its “soul” is the lust that caused the misdeed and accompanied it. Feeling regret for having committed a misdeed destroys the “soul” of the negative energy; confessing verbally – physically using our mouths – destroys the “body” of the negative energy.1” Derech Mitzvotecha, Vidui (pp. 38a ff).