The elders which are among you I exhort, who am also an elder, and a witness of the sufferings of Christ, and also a partaker of the glory that shall be revealed:
Elders - alike in office and age (1 Peter 5:5).
I ... also an elder. To put one's self on a level with those we exhort gives weight to exhortations (cf. 2 John). Peter, in humility, for the Gospel's sake, does not put forward his apostleship, wherein he presided over the elders. In this the apostles have no successors, for 'the signs of an apostle' have not been transmitted. The presidents over the presbyters and deacons, by whatever name designated, angel, bishop, or moderator, etc., though of the same ORDER as the presbyters, yet have virtually succeeded to a superintendency analogous to that exercised by the apostles (this priority existed from the earliest times after the apostles) (Tertullian); just as the Jewish synagogue (the model which the Church followed) was governed by a council of presbyters, presided over by one of themselves, "the chief ruler of the synagogue," (cf. Vitringa, 'Synagogue,' part 2:, chs. 3: and 7:)
Witness - an eye-witness of Christ's sufferings; so qualified to exhort you to believing patience in suffering for well doing after His example (1 Peter 2:20). This explains the 'therefore' in 'Aleph (') A B, 'I therefore exhort,' resuming 1 Peter 4:19. His higher dignity as an apostle is delicately implied, as eye-witnessing was a necessary qualification for apostleship (cf. Peter's own speeches, Acts 1:21-22; Acts 2:32; Acts 10:39).
Also - the righteous recompense corresponding to the sufferings.
Partaker of the glory - according to Christ's promise; an earnest was given in the transfiguration.