'Servitude' in the Bible

David also conquered Moab, then measured them with a cord, making them lie down on the ground. He executed everyone measured out in each two lengths' measurement of the cord, but spared the ones measured out by every third length. Then the Moabites were placed under servitude to David, and made to pay tribute.

David erected garrisons in the Aramean kingdom of Damascus, placing the Arameans under servitude to him, and they paid tribute to him.