2 Samuel 20:4-8

4Then the king said to Amasa, “Summon the men of Judah to come to me within three days, and be here yourself.” 5But when Amasa went to summon Judah, he took longer than the time the king had set for him. 6David said to Abishai, “Now Sheba son of Bikri will do us more harm than Absalom did. Take your master’s men and pursue him, or he will find fortified cities and escape from us.” 7So Joab’s men and the Kerethites and Pelethites and all the mighty warriors went out under the command of Abishai. They marched out from Jerusalem to pursue Sheba son of Bikri. 8While they were at the great rock in Gibeon, Amasa came to meet them. Joab was wearing his military tunic, and strapped over it at his waist was a belt with a dagger in its sheath. As he stepped forward, it dropped out of its sheath.