John Calvin Reformed @genevareformer

8. For God is my witness. He now declares more explicitly his affection for them, and, with the view of giving proof of it, he makes use of an oath, and that on good grounds, because we know how dear in the sight of God is the edification of his Church. It was, too, more especially of advantage, that Paul’s affection should be thoroughly made known to the Philippians.

Matthew Henry Presbyterian @wholebiblehenry

The apostle expresses the ardent affection he had for them, and his concern for their spiritual welfare: I have you in my heart, Phi 1:7. He loved them as his own soul, and they lay near his heart. He thought much of them, and was in care about them. Observe, 1.

Commenting on Philippians 1:7-8

John Gill Reformed Baptist @doctorgill

For God is my record,.... Which is all one as swearing by him; it is in form of an oath, being a solemn appeal to him as the searcher of hearts, for the uprightness of his mind, the sincerity of his expressions, and the strength of his affections: how greatly I long after you all; the common members, as well as the bishops and deacons...