John Gill Commentary 1 Kings 2:35

"And the king put Benaiah the son of Jehoiada in his room over the host; and Zadok the priest did the king put in the room of Abiathar." — 1 Kings 2:35 (ASV)

And the king put Benaiah the son of Jehoiada in his room over
the host
Advanced him from being captain of his bodyguards to be general of the army:

and Zadok the priest did he put in the room of Abiathar ;
from a common priest he promoted him to the high priesthood; whereby that office was restored to its ancient line, the family or Eleazar, having been in the line of Ithamar for many years; and the prediction of the destruction of Eli's house, made eighty years ago, began to be fulfilled, (1 Samuel 2:31–36) .