Philemon 1:9

yet for love's sake I rather beseech, being such a one as Paul the aged, and now a prisoner also of Christ Jesus:

In Paul's times, ambassadors were practically all "old men"; therefore the word for "old men" came to mean also "ambassador." Some distinguished scholars have translated it that way, and it is given as an alternative reading in the ASV margin. However, we believe Lenski is right in saying:

We prefer the reading "old man" to the inferior reading "ambassador," which some commentators prefer by appealing to Ephesians 6:20. The whole idea of ambassadorships is, however, incongruous to the present connection; no commentator has been able to work it into Paul's thought in a convincing way.[22]

Some have objected to the fact that at the approximate age of sixty years when this was written, Paul was not old. In a relative sense, however, he was old. And for one Whose life had been marked by the toils and hardships endured by the beloved apostle, it is not unlikely that many of the visible signs of old age were exhibited in his person.