With Onesimus - Who had been formerly a servant of Philemon, an inhabitant of Colossae; see the notes at Philemon 1:10. Onesimus had probably been recently converted; and Paul felt toward him the warm attachment of a brother; Philemon 1:16. In what way he became acquainted with him is unknown. A more full account of him will be found in the notes at the Epistle to Philemon.
Who is one of you - That is, either who is from your city, or one of your own people and nation. It is clear from this, that Onesimus was from Phrygia, and probably from the city of Colossae itself. It would seem also that he was of a higher rank than is designated by the word “slave” now. He was, indeed, a “servant” δοῦλος doulos - of Philemon, but would the apostle have addressed the Colossians, and said that he was “one of them,” if he had occupied precisely the condition which is now denoted by the word “slave”? Would a minister of the gospel now in the Northern States, who should send a letter by a run-away slave to a community of masters at the South, say of him that he was “one of them?” Would it be kindly received, or produce a good impression, if he did? There is reason, therefore, to think that Onesimus was not a slave in the proper sense, but that he might have been a respectable youth, who had bound himself to service for a term of years; compare Philemon 1:18.
They shall make known to you all things which are done here - Relating to Paul himself and the state of the church in Rome. As the Epistle which Paul sent was designed not only for them, but to be a part of the volume of revealed truth, he wrote only those things which would be of permanent interest. Other matters he left for those who carried the Epistle to communicate. It would also serve to give Tychicus and Onesimus more respectability in view of the church at Colossae, if he referred the church to them for information on important points.