Jamieson, Fausset and Brown on Ezekiel 44:15

15. Zadok--The priests of the line of Ithamar were to be discharged from ministrations in the temple, because of their corruptions, following in the steps of Eli's sons, against whom the same denunciation was uttered (1Sa 2:32, 35). Zadok, according to his name (which means "righteous") and his line, were to succeed (1Ki 2:35; 1Ch 24:3), as they did not take part in the general apostasy to the same degree, and perhaps [Fairbairn] the prophet, referring to their original state, speaks of them as they appeared when first chosen to the office.