1 Kings 2:27

That he might fulfil. The prophecy fulfilled was that of 1 Sam. 2:30-35; 3:11-14. Abiathar was a descendant of the house of Eli and was the sole survivor of the slaughter of the sons of Ahimelech by Doeg (1 Sam. 22:9-23; 23:6). With the deposition of Abiathar, the high priesthood passed from the house of Ithamar to the house of Eleazar, the elder son of Aaron, to which Zadok belonged (Num. 25:11-13; 1 Chron. 24:1-6). Both Abiathar and Zadok had hitherto acted as priests, with some measure of coordination between the two while the tabernacle was at Gibeon under Zadok’s charge, and the ark in Mt. Zion under Abiathar. After the disgrace of Abiathar the dignity of the office of the high priesthood passed to Zadok.

It must not be thought that the purpose of Solomon in humbling Abiathar was merely for the purpose of bringing about the fulfillment of prophecy. His act was prompted solely by the merits of the case. God decrees because He foresees.