2 When he defeated Moab, he measured them with the cord, making them lie on the ground. He measured two cords to kill and ⌊the third cord⌋a to let live.b So Moab became servants of David, bringing tribute.
Literally “the filling of a cord”
This method of selection must have been well known to the reader, but the exact procedure has been obscured over the millennia. It may be that one out of three lived through the process, only to become subservient