Albert Barnes Commentary 1 Kings 1:20

"And thou, my lord the king, the eyes of all Israel are upon thee, that thou shouldest tell them who shall sit on the throne of my lord the king after him." — 1 Kings 1:20 (ASV)

Tell them who shall sit on the throne - Alongside what may be called the natural right of hereditary succession, there existed in the ancient world, and especially in the East, a right, if not of absolutely designating a successor, then at least of choosing one from among several sons. Thus, Cyrus designated Cambyses, and Darius designated Xerxes; and an even more absolute right of nomination was exercised by some of the Roman emperors.