'My Lord the King' in the Bible

Joab said, “May the Lord add to His people a hundred times as many as they are! But, my lord the king, are they not all my lord’s servants? Why then does my lord require this? Why will he bring guilt on Israel?”

Ornan said to David, “Take it for yourself; and let my lord the king do what is good in his eyes. See, I will give you the oxen also for burnt offerings and the threshing sledges (heavy wooden platforms) for wood and the wheat for the grain offering; I give it all.”