"A House For My Name"
It was through Nathan that The Lord decreed to David to make the preparations for the building of the original Temple (see Temples) in Jerusalem:
"You Are The Man!"
It was Nathan who The Lord sent to rebuke King David after his adultery with Bathsheba, and the arranged killing of her husband Uriah:
"Now there came a traveler to the rich man, and he was unwilling to take one of his own flock or herd to prepare for the wayfarer who had come to him, but he took the poor man's lamb, and prepared it for the man who had come to him."
"Then David's anger was greatly kindled against the man; and he said to Nathan, "As The Lord lives, the man who has done this deserves to die; and he shall restore the lamb fourfold, because he did this thing, and because he had no pity."
"Nathan said to David, "You are the man!" Thus says The Lord, the God of Israel, 'I anointed you king over Israel, and I delivered you out of the hand of Saul; and I gave you your master's house, and your master's wives into your bosom, and gave you the house of Israel and of Judah; and if this were too little, I would add to you as much more. Why have you despised the word of The Lord, to do what is evil in His sight? You have smitten Uriah the Hittite with the sword, and have taken his wife to be your wife, and have slain him with the sword of the Ammonites." (2 Samuel 12:1-9 RSV)
Adonijah's Attempt To Take The Throne Thwarted
When David's son Adonijah attempted to succeed David as king in place of Solomon, it was Nathan who revealed the plot to the king and had it stopped:
"Then Nathan said to Bathsheba the mother of Solomon, "Have you not heard that Adonijah the son of Haggith has become king and David our lord does not know it? Now therefore come, let me give you counsel, that you may save your own life and the life of your son Solomon. Go in at once to King David, and say to him, 'Did you not, my lord the king, swear to your maidservant, saying, "Solomon your son shall reign after me, and he shall sit upon my throne"? Why then is Adonijah king?' Then while you are still speaking with the king, I also will come in after you and confirm your words." (1 Kings 1:9-14 RSV)
Fact Finder: Did Nathan write (now lost) records of the reigns of both King David and King Solomon?
1 Chronicles 29:29, 2 Chronicles 9:29