II Samuel 12:7-10

"Then Nathan said to David, 'You are the man! Thus says the Lord God of Israel: "I anointed you king over Israel, and I delivered you from the hand of Saul".'"

"'"I gave you your master's house and your master's wives into your keeping, and gave you the house of Israel and Judah. And if that had been too little, I also would have given you much more"!'"

"'"Why have you despised the commandment of the Lord, to do evil in His site? You have killed Uriah the Hittite with the sword; you have taken his wife to be your wife, and have killed him with the sword of the people of Ammon".'"

"'"Now therefore, the sword shall never depart from your house, because you have despised Me, and have taken the wife of Uriah the Hittite to be your wife".'"

(Remember: God is the same God as the Old Testament. We may have salvation in Christ, but God still hates sin as much as He always has. Sexual immorality is an especially terrible sin to commit, as it's a sin against yourself, others, and God.)