2 Samuel 8:1-2

11Some time later, David attacked the Philistines, and he won the fight against them. He now had power over them and over their towns.

2David also won a battle against the Moabites. He made the Moabite prisoners lie down on the ground. Then he used a piece of rope to measure them into groups. When he had measured two groups, he would tell his men to kill all those prisoners. When he measured the next group, he would let those prisoners stay alive. So the Moabites were now under David's authority and they began to pay taxes to him.