2 Samuel 8:1-2

1And after this it came to pass that David smote the Philistines, and subdued them; and David took the power of the capital out of the hand of the Philistines.

2And he smote the Moabites, and measured them with a line, making them lie down on the ground; and he measured two lines to put to death, and one full line to keep alive. And the Moabites became David's servants, [and] brought gifts.