2 Samuel 8 · a question people ask
Why did David treat Moab so harshly? Wasn't his own family part Moabite?
The chapter doesn't say why. It tells what David did to the Moabites after the battle (8:2) and that they "became servants to David, and brought tribute" (8:2), and nothing more. It gives no reason, and it records no word from the LORD about it. The family link is real. Ruth was one of "the women of Moab" (Ruth 1:4); "Boaz took Ruth and she became his wife" (Ruth 4:13), and their son Obed "is the father of Jesse, the father of David" (Ruth 4:17). And when Saul was hunting him, David asked the king of Moab, "Please let my father and my mother come out to you, until I know what God will do for me" (1 Samuel 22:3), and "they lived with him all the time that David was in the stronghold" (1 Samuel 22:4). The Bible doesn't connect those verses with 8:2, and this answer doesn't either.
The verses
“He defeated Moab, and measured them with the line, making them to lie down on the ground; and he measured two lines to put to death, and one full line to keep alive. The Moabites became servants to David, and brought tribute.”
“They took for themselves wives of the women of Moab. The name of the one was Orpah, and the name of the other was Ruth. They lived there about ten years.”
“So Boaz took Ruth and she became his wife; and he went in to her, and the LORD enabled her to conceive, and she bore a son.”
“The women, her neighbors, gave him a name, saying, “A son is born to Naomi”. They named him Obed. He is the father of Jesse, the father of David.”