1-kings 2:27

So Solomon thrust out Abiathar - This was for having taken part before with Adonijah, but by it a remarkable prophecy was fulfilled; see 1 Samuel 2:13-35 (note), and the notes there. God had told Eli that the priesthood should depart from his house; Abiathar was the last of the descendants of Ithamar, of which family was Eli the high priest. Zadok, who was made priest in the stead of Abiathar, was of the family of Eliezer; and by this change the priesthood reverted to its ancient channel. Abiathar deserved this degradation; he supported Adonijah in his unnatural assumption of the royal dignity, even during the life of his father. This was the head and front of his offending.

That he might fulfil the word of the L RD - We need not understand this as stating that the fulfillment of the old prophecy was Solomon's motive, or even one of his motives. The reference is to the overruling providence of God, which thus brought about the fulfillment of the prophecy. (Compare Matthew 1:22; Matthew 2:15; Matthew 27:35, etc.) The deposition of Abiathar involved the rejection of the house of Ithamar 1 Chronicles 24:3, to which Eli belonged, and the reestablishment of the high priesthood in the line of Eleazar.

2:27 Which he spake - Concerning the translation of the priesthood from the house of Eli, and of Ithamar, to that of Eleazar: whichbeing threatened eighty years ago, is now executed. So divine vengeance,though sometimes it be slow, is always sure.