1 Samuel 24:8

Saul apparently had withdrawn from his men, and David seizes the opportunity of proving to him his innocence, and quieting the king's fears. He goes out, therefore, and calls after him, saying, My lord the king, addressing him thus as his master, to whom his obedience was due. He also pays him the utmost reverence, bowing his face to the earth and making obeisance. By this lowly bearing David showed that, so far from being a rebel, he still acknowledged Saul's lawful authority, and was true to his allegiance.