1 Kings 2:15, 22-24

So he said, “You know that the kingdom belonged to me [as the eldest living son] and all Israel looked to me and expected me to be king. However, the kingdom has passed [from me] and became my brother’s, for it was his from the LORD.

King Solomon answered and said to his mother, “And why are you asking for Abishag the Shunammite for Adonijah? Ask the kingdom for him also—since he is my older brother—[ask it] for him and for Abiathar the priest and Joab the son of Zeruiah [his supporters]!” Then King Solomon swore by the LORD, saying, “May God do the same to me, and more also, if Adonijah has not requested this [deplorable] thing against his own life. So now, as the LORD lives, who has established me and set me on the throne of David my father, and who has made me a house as He promised, Adonijah shall indeed be put to death today.”