Deuteronomy 17:15

thou shalt in any wise, by all means, set him king over thee whom the Lord, thy God, shall choose, 1 Samuel 9:15; one from among thy brethren shalt thou set king over thee; thou mayest not set a stranger over thee, which is not thy brother. The ideal which God had in mind for Israel was a theocracy, a direct government of the people by the Lord; but He was willing to modify that to the extent of letting a man chosen by Him, from among the children of Israel, be king as His representative.