David's experience/prayers after he was involved with adultery and murder are found in
Psalms 32 and 51. New Testament word for us if we fall/fail Him or whenever we fail, big failure or small failure is found in 1 John chapter 1 and the first verses of chapter 2:
5 This then is the message which we have heard of him, and declare unto you, that God is light, and in him is no darkness at all 6 If we say that we have fellowship with him, and walk in darkness, we lie, and do not the truth: 7 But if we walk in the light, as he is in the light, we have fellowship one with another, and the blood of Jesus Christ his Son cleanseth us from all sin.
8 If we say that we have no sin, we deceive ourselves, and the truth is not in us. 9 If we confess/admit our sins, he is faithful and just to forgive us our sins, and to cleanse us from all unrighteousness. 10 If we say that we have not sinned, we make him a liar, and his word is not in us.
1 My little children, these things write I unto you, that ye sin not. And if any man sin, we have an advocate with the Father, Jesus Christ the righteous:
2 And he is the propitiation (mercy seat) for our sins: and not for ours only, but also for the sins of the whole world.
Here is
Psalm 132 from the NLT
1 Oh, what joy for those
whose disobedience is forgiven,
whose sin is put out of sight!
2 Yes, what joy for those
whose record the Lord has cleared of guilt,
whose lives are lived in complete honesty!
3 When I refused to confess my sin,
my body wasted away,
and I groaned all day long.
4 Day and night your hand of discipline was heavy on me.
My strength evaporated like water in the summer heat.
5 Finally, I confessed all my sins to you
and stopped trying to hide my guilt.
I said to myself, “I will confess my rebellion to the Lord.”
And you forgave me! All my guilt is gone.
6 Therefore, let all the godly pray to you while there is still time,
that they may not drown in the floodwaters of judgment.
7 For you are my hiding place;
you protect me from trouble.
You surround me with songs of victory.
8 The Lord says, “I will guide you along the best pathway for your life.
I will advise you and watch over you.
9 Do not be like a senseless horse or mule
that needs a bit and bridle to keep it under control.”
10 Many sorrows come to the wicked,
but unfailing love surrounds those who trust the Lord.
11 So rejoice in the Lord and be glad, all you who obey him!
Shout for joy, all you whose hearts are pure!
Here is
Psalm 51 from the NLT
1 Have mercy on me, O God,
because of your unfailing love.
Because of your great compassion,
blot out the stain of my sins.
2 Wash me clean from my guilt.
Purify me from my sin.
3 For I recognize my rebellion;
it haunts me day and night.
4 Against you, and you alone, have I sinned;
I have done what is evil in your sight.
You will be proved right in what you say,
and your judgment against me is just.
5 For I was born a sinner—
yes, from the moment my mother conceived me.
6 But you desire honesty from the womb,
teaching me wisdom even there.
7 Purify me from my sins, and I will be clean;
wash me, and I will be whiter than snow.
8 Oh, give me back my joy again;
you have broken me—
now let me rejoice.
9 Don’t keep looking at my sins.
Remove the stain of my guilt.
10 Create in me a clean heart, O God.
Renew a loyal spirit within me.
11 Do not banish me from your presence,
and don’t take your Holy Spirit from me.
12 Restore to me the joy of your salvation,
and make me willing to obey you.
13 Then I will teach your ways to rebels,
and they will return to you.
14 Forgive me for shedding blood, O God who saves;
then I will joyfully sing of your forgiveness.
15 Unseal my lips, O Lord,
that my mouth may praise you.
16 You do not desire a sacrifice, or I would offer one.
You do not want a burnt offering.
17 The sacrifice you desire is a broken spirit.
You will not reject a broken and repentant heart, O God.
18 Look with favor on Zion and help her;
rebuild the walls of Jerusalem.
19 Then you will be pleased with sacrifices offered in the right spirit—
with burnt offerings and whole burnt offerings.
Then bulls will again be sacrificed on your altar.