1 Samuel 2:35

35. I will raise me up a faithful priest By this “faithful priest” some have understood Samuel, and others Zadok, while a few argue that both of them may be intended. Samuel, indeed, succeeded Eli as judge of Israel, and during his lifetime the Aaronic priesthood seems to have fallen into neglect; but it is certain that neither he nor his descendants were established in the priesthood, so that it cannot be said that God “built him a sure house.” Therefore it is better to understand Zadok to be this faithful priest. As a part of this prophecy received its fulfilment in the thrusting out of Abiathar, so this verse was fulfilled in the consecration of Zadok. 1Ki 2:35 ; 1 Chronicles 29:22. Zadok was a descendant of Aaron through Eleazar, (1 Chronicles 24:3,) and therefore God’s promise to Aaron was not made void by the impiety of Eli’s sons, for in Zadok, Eleazar’s posterity were established forever. Compare Numbers 25:11-13. It is also well worthy of notice that in the temple of Ezekiel’s vision, which symbolizes the spiritual Church of the then future, the sons of Zadok are named as priests. Ezekiel 40:46; Ezekiel 43:19; Ezekiel 44:15; Ezekiel 48:11.

He shall walk before mine anointed for ever Before David, Solomon, and the later kings of Judah, until the passing away of the Hebrew monarchy before the Messianic kingdom, in which Christ himself is prophet, priest, and king.