Abiathar had supported Adonijah in his attempt to make himself king (1 Kings 1:7, 25). But he was removed from his position instead of being killed because he had:
carried the ark (2 Samuel 15:24, 29, 35),
supported David, and
shared in David's hardships.
Abiathar's removal from the priesthood fulfilled God's word about Eli's family line through Ithamar (1 Samuel 2:30–35). Zadok's appointment (1 Kings 4:2) restored the high priesthood to Eleazar's line, as it was before Eli (Numbers 20:22–28; 25:11–13; 2 Samuel 8:17; 1 Chronicles 6:1–8, 50–53; Ezra 7:2–5) and continued during Israel's divided kingdom (2 Chronicles 31:10; Ezekiel 43:19).