The Apostle Paul
1 Thessalonians 3:6BSB·traditional attribution

But just now, Timothy has returned from his visit with the good news about your faith, your love, and the fond memories you have preserved, longing to see us just as we long to see you.

John Calvin Reformed @genevareformer

He shews here, by another argument, by what an extraordinary affection he was actuated towards them, inasmuch as he was transported almost out of his senses by the joyful intelligence of their being in a prosperous condition. For we must take notice of the circumstances which he relates. He was in affliction and necessity: there might have seemed, therefore, no room for cheerfulness.

Matthew Henry Presbyterian @wholebiblehenry

Here we have Paul's great satisfaction upon the return of Timothy with good tidings from the Thessalonians, in which we may observe, I. The good report Timothy made concerning them, Th1 3:6. Without question, he was a willing messenger of these good tidings. Concerning their faith, that is, concerning their stedfastness in the faith, that they were not shaken in mind, nor turned aside form the profession of the gospel.

Commenting on 1 Thessalonians 3:6-10

John Gill Reformed Baptist @doctorgill

But now when Timotheus came from you unto us,.... At Corinth, as appears from Act 18:5 which shows that this epistle was not written from Athens, as the subscription to it asserts, but from Corinth; for as soon as ever Timothy came from Thessalonica, to the apostle at Corinth, and made the report to him, he immediately sent them this epistle which is here suggested: "but, now", &c.