Whom I have sent unto you - The churches where Paul had preached, would feel a great interest in his welfare. He was a prisoner at Rome, and it was doubtful what the result would be. In this situation, he felt it proper to despatch a special messenger to give information about his condition; to state what was doing in Rome; to ask the prayers of the churches; and to administer consolation to them in their various trials. The same sentiment in regard to the embassy of Tychicus, is expressed in the Epistle to the Colossians, Colossians 4:7-8. No small part of the consolation which he would impart to them would be found in these invaluable letters which he bore to them from the apostle.

Whom I have sent - for the same purpose - Namely, that the Ephesians might know his affairs, and those of the Church at Rome: messengers of this kind frequently passed between the Churches in those ancient times.
Comfort your hearts - By showing you how powerfully he was upheld in all his tribulations, and how God turned his bonds to the furtherance of the Gospel. This must have been great consolation to all the followers of God; and particularly to those in Ephesus or Laodicea, or to whomsoever the epistle was directed. The question, To whom was it sent? is divided between the Ephesians and the Laodiceans. Dr. Lardner has argued strongly in favor of the former; Dr. Paley not less so in favor of the latter.

Whom I have sent unto you for the same purpose,.... Which shows the great concern the apostle had for the churches, being willing to inform them of everything that might be for their use and service:
that ye might know our affairs; temporal and spiritual, and not only the apostle's affairs, but the affairs of those that were with him, who were concerned in the same common cause:
and that he might comfort your hearts; both by such a relation, and by the ministry of the Gospel to them: believers in Christ are sometimes disconsolate, by reason of indwelling sin, Satan's temptations, the hidings of God's face, afflictions and persecutions, their own sufferings, and those of others; and it is the business of the ministers of Christ to comfort them; their commission is to speak comfortably to them; and they are qualified for it, by inward comforts in their own souls; the Gospel they preach, and the message they bring, is of a comfortable nature; the Spirit of God acts by them, and with them as a comforter; and sad indeed is the state of Zion, or the church of Christ, when it has no comforters.

for the same purpose--Greek, "for this very purpose." Colossians 4:8 is almost word for word the same as this verse.
our affairs--Greek, "the things concerning us," namely, concerning myself. "Aristarchus, my fellow prisoner, and Marcus, sister's son to Barnabas" (Colossians 4:10).

That he might comfort your hearts - By relating the supports I find from God, and the success of the gospel.