The Apostle Paul
Philippians 1:5ESV·traditional attribution

because of your partnership in the gospel from the first day until now.

John Calvin Reformed @genevareformer

5 For your fellowship. He now, passing over the other clause, states the ground of his joy — that they had come into the fellowship of the gospel, that is, had become partakers of the gospel, which, as is well known, is accomplished by means of faith; for the gospel appears as nothing to us, in respect of any enjoyment of it, until we have received it by faith.

Matthew Henry Presbyterian @wholebiblehenry

The apostle proceeds after the inscription and benediction to thanksgiving for the saints at Philippi. He tells them what it was he thanked God for, upon their account. Observe here, I. Paul remembered them: he bore them much in his thoughts; and though they were out of sight, and he was at a distance from them, yet they were not out of his mind: or...

Commenting on Philippians 1:3-6

John Gill Reformed Baptist @doctorgill

For your fellowship in the Gospel,.... Or "for your communication unto the Gospel"; that is, to the support of it. These Philippians were one of the churches of Macedonia the apostle so highly commends for their liberality in Co2 8:1; they had been very communicative to him, and those that were with him, from the beginning of the Gospel being preached to them: as the...