Repentance in the Old Testament
Ezekiel 18:21-22 KJV
21 But if the wicked will turn from all his sins that he hath committed, and keep all my statutes, and do that which is lawful and right, he shall surely live, he shall not die.
22 All his transgressions that he hath committed, they shall not be mentioned unto him:in his righteousness that he hath done he shall live.
While repentance and baptism are not practiced in the Old Testament. Living a consecrated life only to God is taught.