1 Kings 2:22 - Albert Barnes' Notes on the Bible

Ask for him the kingdom also - Bath-sheba had not seen anything dangerous or suspicious in Adonijah’s request. Solomon, on the contrary, takes alarm at once. To ask for Abishag was to ask for the kingdom. To the Oriental mind a monarch was so sacred, that whatever was brought near to him was thenceforth separate from common use. This sacred and separate character attached especially to the Royal harem. The inmates either remained widows for the rest of their lives, or became the wives of the deceased king’s successor. When a monarch was murdered, or dethroned, or succeeded by one whose title was doubtful, the latter alternative was almost always adopted (compare 2 Samuel 12:8; 2 Samuel 16:22). Public opinion so closely connected the title to the crown and the possession of the deceased monarch’s wives, that to have granted Adonijah’s request would have been the strongest encouragement to his pretensions. Solomon, seeing this, assumes that Adonijah cherishes a guilty purpose, that there has been a fresh plot, that Abiathar and Joab - Adonijah’s counselors in the former conspiracy 1 Kings 1:7 - are privy to it, and that the severest measures are necessary to crush the new treason.