When Jethro bestowed his daughter Zipporah upon Moses as his wife, he said to his future son-in-law: "I know that thy father Jacob took his wives, the daughters of Laban, and went away with them against their father's will. Now take an oath that thou wilt not do the same unto me," and Moses swore not to leave him without his consent, and he remained with Jethro, who made him the shepherd of his flocks. By the way he tended the sheep, God saw his fitness to be the shepherd of His people, for God never gives an exalted office to a man until He has tested him in little things. Thus Moses and David were tried as shepherds of flocks, and only after they had proved their ability as such, He gave them dominion over men.