“In the LORD’s hand the king’s heart is a stream of water that he channels toward all who please him.” The king was a powerful person in ancient Israelite society, but even a person this powerful is subservient to the will of YHWH. Government works best when the leader is “in the Lord’s hand”. (NOTE: This is WAY different from advocating theocracy.) “The Lord’s hand” means he is lives in the presence and power of God, and uses that place and his position to do good for humankind.
A governmental leader needs to do more than just follow the Lord. He needs to do more than just love the Lord. He needs to be in the Lord’s hand—submitted and following obediently. He needs to be the Lord’s representative, doing everything the Lord would do in the manner and with the motives that the Lord would do it.
If he/she will do that, his or her “heart is a stream of water.” The stream of water represents life, nourishment, and nurture. The king was the Lord’s presence on the earth. He was his justice, and he was his life-giving force. In addition to that, he was the means by which the Lord gave his message to the people. In return, God will incline the king in good directions.