I exhort the elders among you, as a fellow elder, and a witness of the sufferings of Christ, and who will also share in the glory that will be revealed.
and a witness of the sufferings of Christ: In that Peter was an apostle, he had seen the suffering of Christ (Acts 1:8), His death, and the resurrected Christ. Peter was an eyewitness who had been called forth to testify (Acts 3:15; Acts 10:39).