I Chronicles - Chapter 19
A Beard, More or Less
Later, King Nachash of Ammon died and David sent a group to pay a condolence call to his son Chanun. Chanun suspected that they were spies, so he had their beards shaved and the seats of their pants cut out. David was informed of the humiliation of his messengers and he instructed them to remain in Jericho until their beards grew back. (The account in II Samuel chapter 10 says that Chanun had half of each man's beard cut off. That detail is not stressed here, as Chronicles has a different focus.)
Chanun realized that he had made a huge error in judgment and that war was inevitable, so he decided to wage a preemptive strike against Israel. They hired mercenary armies to bolster their ranks. David learned of this, so he dispatched Yoav and his forces. Yoav divided his army so that they could fight on two fronts with the understanding that if either faction was in trouble, the other would come to their rescue. The hired soldiers from Aram fled, followed by the Ammonite forces themselves. The Aramite mercenaries regrouped, but David's army defeated them again, this time killing Shofach, their general. After that, Aram made peace with Israel and would no longer allow Ammon to hire their army.