Bible Verses About Repentance: Necessary to the pardon of sin

But Peter said to them: Do penance: and be baptized every one of you in the name of Jesus Christ, for the remission of your sins. And you shall receive the gift of the Holy Ghost.

Be penitent, therefore, and be converted, that your sins may be blotted out.

Do penance therefore for this thy wickedness: and pray to God, that perhaps this thought of thy heart may be forgiven thee.