2 Samuel 3:22-39
Just then the servants of David arrived with Jo'ab from a raid, bringing much spoil with them. But Abner was not with David at Hebron, for he had sent him away, and he had gone in peace. When Jo'ab and all the army that was with him came, it was told Jo'ab, "Abner the son of Ner came to the king, and he has let him go, and he has gone in peace."
Then Jo'ab went to the king and said, "What have you done? Behold, Abner came to you; why is it that you have sent him away, so that he is gone? You know that Abner the son of Ner came to deceive you, and to know your going out and your coming in, and to know all that you are doing."
When Jo'ab came out from David's presence, he sent messengers after Abner, and they brought him back from the cistern of Sirah; but David did not know about it. And when Abner returned to Hebron, Jo'ab took him aside into the midst of the gate to speak with him privately, and there he smote him in the belly, so that he died, for the blood of As'ahel his brother. Afterward, when David heard of it, he said, "I and my kingdom are for ever guiltless before the LORD for the blood of Abner the son of Ner. May it fall upon the head of Jo'ab, and upon all his father's house; and may the house of Jo'ab never be without one who has a discharge, or who is leprous, or who holds a spindle, or who is slain by the sword, or who lacks bread!"
So Jo'ab and Abi'shai his brother slew Abner, because he had killed their brother As'ahel in the battle at Gibeon. Then David said to Jo'ab and to all the people who were with him, "Rend your clothes, and gird on sackcloth, and mourn before Abner." And King David followed the bier. They buried Abner at Hebron; and the king lifted up his voice and wept at the grave of Abner; and all the people wept. And the king lamented for Abner, saying, "Should Abner die as a fool dies? Your hands were not bound, your feet were not fettered; as one falls before the wicked you have fallen." And all the people wept again over him.
Then all the people came to persuade David to eat bread while it was yet day; but David swore, saying, "God do so to me and more also, if I taste bread or anything else till the sun goes down!" And all the people took notice of it, and it pleased them; as everything that the king did pleased all the people. So all the people and all Israel understood that day that it had not been the king's will to slay Abner the son of Ner. And the king said to his servants, "Do you not know that a prince and a great man has fallen this day in Israel? And I am this day weak, though anointed king; these men the sons of Zeru'iah are too hard for me. The LORD requite the evildoer according to his wickedness!"