1 Samuel 2:30

Wherefore the Lord God of Israel saith
This being the case, so much contempt cast upon his sacrifices, and dishonour on himself:

I said indeed that thy house, and the house of thy father, should
walk before me for ever;
or minister in the priest's office before him: if the house of Aaron in general is meant, it did continue so to do, in one branch or another of it, as long as the Mosaic dispensation lasted, which is meant by the phrase "for ever"; but since it is afterwards denied that it should, rather the house of Ithamar, or of the immediate parent of Eli, is meant, and this said when the priesthood was translated from the family of Eleazar to the family of Ithamar; when, and on what account that was done, we nowhere read. It is a tradition ^F6, that it was in the time of the Levite's concubine; and because Phinehas, and the other priests, did not go from city to city, and reprove the Israelites for the many sins they were fallen into, that the priesthood was taken away out of the family of Eleazar, and translated to that of Ithamar:

but now the Lord saith, be it far from me;
to continue the priesthood in the line of Ithamar; which argues no change in the purposes or promises of God, this being not a decree of his, but a declaration of his will; that if the house of Ithamar behaved well in the discharge of the office of the high priest, it should continue with them to the end of the Mosaic dispensation, but if not, it should be taken from them, and restored to the family of Eleazar; as it was in Solomon's time:

for them that honour me I will honour;
as Phinehas the son of Eleazar did at Shittim, where he showed his zeal for the Lord of hosts, and had the promise of the everlasting priesthood; and which continued in his family until the Babylonish captivity, excepting the interval in which it was in the family of Ithamar, and for what reason is not known:

and they that despise me shall be lightly esteemed;
as the posterity of Eli, whose sons despised the Lord, and his offerings, as appeared by their conduct; and these were killed in battle in one day, and in the times of Solomon, Abiathar, of the posterity of Eli, was thrust out of the priesthood, and Zadok, of the line of Eleazar, was put in his room, ( 1 Kings 2:27 1 Kings 2:35 ) .