The Shorter Catechism
Question 87: What is repentance unto life?
Answer: Repentance unto life is a saving grace, whereby a sinner, out of a true sense of his sin, and apprehension of the mercy of God in Christ, doth, with grief and hatred of his sin, turn from it unto God, withpu full purpose of, and endeavour after, new obedience.
A parable of the Lord Jesus Christ regarding prayer with acknowledgment of sin.
Luke 18:9 And he spake this parable unto certain which trusted in themselves that they were righteous, and despised others:
18:10 Two men went up into the temple to pray; the one a Pharisee, and the other a publican.
18:11 The Pharisee stood and prayed thus with himself, God, I thank thee, that I am not as other men [are], extortioners, unjust, adulterers, or even as this publican.
18:12 I fast twice in the week, I give tithes of all that I possess.
18:13 And the publican, standing afar off, would not lift up so much as [his] eyes unto heaven, but smote upon his breast, saying, God be merciful to me a sinner.
18:14 I tell you, this man went down to his house justified [rather] than the other: for every one that exalteth himself shall be abased; and he that humbleth himself shall be exalted.
As we by nature are destitute, so we must ask God for mercy.
Micah 7:18 Who [is] a God like unto thee, that pardoneth iniquity, and passeth by the transgression of the remnant of his heritage? he retaineth not his anger for ever, because he delighteth [in] mercy.