2 Samuel 8:2

And he smote Moab, east and southeast of the Dead Sea, and measured them with a line, casting them down to the ground; even with two lines measured he to put to death, and with one full line to keep alive. It was a very severe punishment which was here meted out to the Moabites, since their soldiers were compelled to lie down on the ground, two thirds of them being measured for death and one-third for life. And so the Moabites, with only a third of their warriors remaining, became David's servants and brought gifts, that is, paid tribute-money.