The Apostle Paul
Romans 1:14ESV·traditional attribution

I am under obligation both to Greeks and to barbarians, both to the wise and to the foolish.

John Calvin Reformed @genevareformer

14. I am a debtor both to the Greeks and to the Barbarians, etc. Those whom he means by the Greeks and the Barbarians, he afterwards explains by adding, both to the wise and to the foolish; which words Erasmus has not rendered amiss by “learned and unlearned,” (eruditos et rudes,) but I prefer to retain the very words of Paul.

Matthew Henry Presbyterian @wholebiblehenry

We may here observe, I. His thanksgivings for them (Rom 1:8): First, I thank my God. It is good to begin every thing with blessing God, to make that the alpha and omega of every song, in every thing to give thanks. - My God. He speaks this with delight and triumph.

Commenting on Romans 1:8-15

John Gill Reformed Baptist @doctorgill

I am a debtor both to the Greeks, and to the Barbarians,.... The meaning is, that he was obliged by the call he had from God, the injunction that was laid upon him by him, and the gifts with which he was qualified, to preach the Gospel to all sorts of men; who are here distinguished into Greeks and Barbarians: sometimes by Greeks are meant...