13. how through infirmity--rather, as Greek, "Ye know that because of an infirmity of my flesh I preached," &c. He implies that bodily sickness, having detained him among them, contrary to his original intentions, was the occasion of his preaching the Gospel to them.
      at the first--literally, "at the former time"; implying that at the time of writing he had been twice in Galatia. See my Introduction; also see on Ga 4:16, and Ga 5:21. His sickness was probably the same as recurred more violently afterward, "the thorn in the flesh" (2Co 12:7), which also was overruled to good (2Co 12:9, 10), as the "infirmity of the flesh" here.

JFB.