Midrash sur Samuel 2 12:6

R. Huna said: "How little does he whom the Lord supports, need to grieve or trouble himself. Saul committed only one sin and was discharged from royalty. David committed two sins, and yet retained it." "Saul committed only one sin." What was it? That of Agag. But did he not commit another sin when he massacred the priests of Nob? Nevertheless only at the incident of Agag it is written (I Sam. 15, 11) I regret that I have set tip Saul as a king. "David committed two sins." What are they? That of Uriah and his numbering of Israel. But there is a third one? That of Bath Sheba? For Bath Sheba he was punished, as it is written (II Sam. 12, 6) For the ewe he shall pay fourfold. What were the four punishments? The death of Bath-Sheba's first child, the death of Amnon, the misfortune of Tamar, and of Absalom. If so, then, was he punished also for numbering Israel? As it is written (II Sam. 24, 15) And the Lord sent a pestilence in Israel from the morning even to the time appointed. In that case he himself was not punished, but in the instances we mentioned, he was personally punished, as R. Juda said in the name of Rab: "For six months David became leprous, and the Sanhedrin separated themselves from him, and the Shechina departed from him, as it is said (Ts. 119, 79) Let those that fear Thee return unto me, and those that knew Thy testimonies, and it is written again (Ib. 51, 14) Restore unto me the gladness of Thy salvation." But has not Rab said that David listened to slander? [Hence he committed more sins?] The former statement is in accordance with the opinion of Samuel who holds that David did not listen to slander. And Rab who holds that David did listen, explains that David had also been punished for it; for R. Juda said in the name of Rab: "At the time when David said unto Mephibosheth (II Sam. 19, 30), Thou and Ziba shall divide the field, a Bath-Kol went forth and said, 'Rechabam and Jeroboam will divide thy Kingdom.' "

King David said before the Holy One Blessed be He. King David said before the Holy One Blessed be He: Let my transgression before You (with Bathsheva) not be written after me. The L-rd: Is it not sufficient for you that people not say: "Because he loved him, He forgave him"? An analogy: A man borrowed from the king twenty kor of wheat a year, and people said: Can this man possibly have met such a debt? It must be that the king forgave him and wrote him a settlement. Once, the king sent (demanding payment), and he did not pay, at which the king entered his house and took his sons and daughters and put them up (for sale) at the auction block — whereupon everyone knew that he had nothing (i.e., that he had not been pardoned.) Here, therefore, all of the punishments that came upon David were publicized and doubled, viz. (II Samuel 12:6) "And he (David) must pay four for the ewe." R. Chananiah says: "arbatayim" — sixteen.