Kitto's Popular Cyclopedia of Biblial Literature
Adoni´jah (Jehovah [is] my Lord) the fourth son of David, by Haggith. He was born after his father became king, but when he reigned over Judah only (2 Samuel 3:4). According to the Oriental notion developed in the article Absalom Adonijah might have considered his claim superior to that of his eldest brother Amnon, who is supposed to have been born while his father was in a private station; but not to that of Absalom, who was not only his elder brother, and born while his father was a king, but was of royal descent on the side of his mother. When, however, Amnon and Absalom were both dead, he became, by order of birth, the heir-apparent to the throne. But this order had been set aside in favor of Solomon, who was born while his father was king of all Israel. Absalom perished in attempting to assert his claim of primogeniture, in opposition to this arrangement. Unawed by this example, Adonijah assumed the state of an heir-apparent, who, from the advanced age of David, must soon be king. But it does not appear to have been his wish to trouble his father as Absalom had done; for he waited till David appeared at the point of death, when he called around him a number of influential men, whom he had previously gained over, and caused himself to be proclaimed king. This was a formidable attempt to subvert the appointment made by the Divine king of Israel; for Adonijah was supported by such men as Joab, the general-in-chief, and Abiathar, the high-priest; both of whom had followed David in all his fortunes. But his plot was, notwithstanding, defeated by the prompt measure taken by David, who directed Solomon to be at once proclaimed, and crowned, and admitted to the real exercise of the sovereign power. Adonijah then saw that all was lost, and fled to the altar, which he refused to leave without a promise of pardon from King Solomon. This he received, but was warned that any further attempt of the came kind would be fatal to him. Accordingly, when, sometime after the death of David, Adonijah covertly endeavoured to reproduce his claim through a marriage with Abishag, the virgin widow of his father [ABISHAG], his design was at once penetrated by the king, by whose order he was instantly put to death (1 Kings 1; 1 Kings 2:13-25).
Kitto, John, ed. Entry for 'Adonijah'. "Kitto's Popular Cyclopedia of Biblial Literature". https://www.studylight.org/encyclopedias/eng/kbe/a/adonijah.html.