Psalm 51:2-3 Wash me thoroughly from my iniquity, and cleanse me from my sin. For I acknowledge my transgressions, and my sin is always before me.
Psalm 51, was the prayer of repentance of David after Nathan the prophet confronted him for committing adultery with Bathsheba.
David's abominable sins
In 2Sam 11:3-5, when David found that Uriah's wife Bethsheba was pregnant, he sent for Uriah. After getting him drunk, David sent him home to his wife but he refused. With his deception a failure, he sent him back to the battlefield. David instructed Joab to send Uriah to the front line and get him killed by withdrawing the other soldiers.
2Sam 12:11-12 Thus says the Lord: 'Behold, I will raise up adversity against you from your own house; and I will take your wives before your eyes and give them to your neighbor, and he shall lie with your wives in the sight of this sun. For you did it secretly, but I will do this thing before all Israel, before the sun.'"
The prophet Nathan told King David that the unborn child would die and all his wives would be taken by another in the sight of all because of his many abominable sins.
2Sam 12:13-14 So David said to Nathan, "I have sinned against the Lord." And Nathan said to David, "The Lord also has put away your sin; you shall not die. However, because by this deed you have given great occasion to the enemies of the Lord to blaspheme, the child also who is born to you shall surely die."
When David humbled himself, repented of his sins and gracefully accepted the extremely painful, sorrowful and harsh judgements of God, God forgave all his abominable sins.
Saul's disobedience and sins
1Sam 13:12-13 then I said, 'The Philistines will now come down on me at Gilgal, and I have not made supplication to the Lord.' Therefore I felt compelled, and offered a burnt offering." And Samuel said to Saul, "You have done foolishly. You have not kept the commandment of the Lord your God, which He commanded you. For now the Lord would have established your kingdom over Israel forever.
Saul blamed Samuel for coming late and gave many excuses, he did not sincerely accept nor confess his sins.
1Sam 15:20-21 And Saul said to Samuel, "But I have obeyed the voice of the Lord... But the people took of the plunder, sheep and oxen, the best of the things which should have been utterly destroyed, to sacrifice to the Lord your God in Gilgal."
Again Saul blamed his people and said that these animals were taken as sacrifices to God.
1Sam 15:22-23 So Samuel said: "Has the Lord as great, delight in burnt offerings and sacrifices, as in obeying the voice of the Lord Behold, to obey is better than sacrifice, and to heed than the fat of rams. For rebellion is as the sin of witchcraft, and stubbornness is as iniquity and idolatry. Because you have rejected the word of the Lord, He also has rejected you from being king."
Brethren, let's be like David, humble ourselves before God, accept our mistakes and weaknesses, repent of our sins, keep the word of God as truth and His chastisements as our refinements, so that He can continue to use us mightily for His glory. Let's not be wise in our own understanding, like the arrogant Saul, but faithfully keep Jesus' words and teachings without doubt.
If we reject His words, He will reject us as His servants. No wonder they are so many depraved (covetous, worldly, carnal, sensual, homosexual and heretic) Christians leaders today.