Galatians 4:19

That the apostle might the better dispose these Christians to bear with him in the reproofs which he was obliged to give them, he here expresses his great affection to them, and the very tender concern he had for their welfare: he was not like them - one thing when among them and another when absent from them. Their disaffection to him had not removed his affection from them; but he still bore the same respect to them which he had formerly done, nor was he like their false teachers, who pretended a great deal of affection to them, when at the same time they were only consulting their own interest; but he had a sincere concern for their truest advantage; he sought not theirs, but them. They were too ready to account him their enemy, but he assures them that he was their friend; nay, not only so, but that he had the bowels of a parent towards them. He calls them his children, as he justly might, since he had been the instrument of their conversion to the Christian faith; yea, he styles them his little children, which, as it denotes a greater degree of tenderness and affection to them, so it may possibly have a respect to their present behaviour, whereby they showed themselves too much like little children, who are easily wrought upon by the arts and insinuations of others.

— Matthew Henry's Concise Commentary (public domain)

My little children-- (Ti1 1:18; Ti2 2:1; Jo1 2:1). My relation to you is not merely that of one zealously courting you (Gal 4:17-18), but that of a father to his children (Co1 4:15). I travail in birth--that is, like a mother in pain till the birth of her child. again--a second time. The former time was when I was "present with you" (Gal 4:18; compare Note, see on Gal 4:13). Christ be formed in you--that you may live nothing but Christ, and think nothing but Christ (Gal 2:20), and glory in nothing but Him, and His death, resurrection, and righteousness (Phi 3:8-10; Col 1:27).

— Jamieson-Fausset-Brown Commentary (public domain)