Today is the feast of St. Polycarp, Bishop and Martyr. Polycarp was a student of the apostle John, ordained by him in Smyrna; we know this from St. Irenaeus, who as a young man heard him preach, and these points are confirmed by others. He was, by all accounts, quite old by the time he was martyred. According to himself, he had lived at least eighty-six years before his martyrdom, which was probably in the 150s, but we don't now if he meant that he was eighty-six then or if it had been eighty-six years since his baptism (and we don't know if he was baptized as an infant, a youth, or a young man). As one of the Apostolic Fathers, he is (with St. Ignatius and St. Clement) a major source of our information about the Christian generations immediately after the Apostles.
From his letter to the Philippians (Chapter XII):
For I trust that ye are well versed in the Sacred Scriptures, and that nothing is hid from you; but to me this privilege is not yet granted. It is declared then in these Scriptures, "Be ye angry, and sin not," and, "Let not the sun go down upon your wrath." Happy is he who remembers this, which I believe to be the case with you. But may the God and Father of our Lord Jesus Christ, and Jesus Christ Himself, who is the Son of God, and our everlasting High Priest, build you up in faith and truth, and in all meekness, gentleness, patience, long-suffering, forbearance, and purity; and may He bestow on you a lot and portion among His saints, and on us with you, and on all that are under heaven, who shall believe in our Lord Jesus Christ, and in His Father, who raised Him from the dead. Pray for all the saints. Pray also for kings, and potentates, and princes, and for those that persecute and hate you, and for the enemies of the cross, that your fruit may be manifest to all, and that ye may be perfect in Him.
The details of St. Polycarp's martyrdom are found in The Martyrdom of Polycarp, one of the earliest Christian hagiographies, compiled by the church at Smyrna, probably within a few decades of his death. It's often reliable as to details, although it likely is filtered through the church at Smyrna's yearly commemoration of his death; some people have argued that its account of the actual legal proceedings is implausible, but inaccuracies are a common issue with portrayals of legal proceedings in all ages (including our own), and this would be particularly true if what we are getting is not direct transcripts of the trials but the trial as it was remembered and commemorated by the local congregation. In any case, The Martyrdom of Polycarp is itself a valuable source of information about views and attitudes in the age of the Apostolic Fathers.