5 I would, however, proceed to a more searching and diligent consideration and handling of these words, had I not other places of his Epistles much more manifest, by comparing which, both these are made more clearly manifest, and if these were not in existence, those others would suffice. To the Corinthians, namely, writing of this same thing, he says thus, “Am I not free? Am I not an Apostle? Have I not seen Christ Jesus our Lord? Are you not my work in the Lord?
If to others I am not an Apostle, to you assuredly I am. For the seal of mine Apostleship are you in the Lord. My defense to them which interrogate me is this. Have we not power to eat and to drink? Have we not power to lead about a woman who is a sister, as also the other Apostles, and the brethren of the Lord, and Cephas?” See how first he shows what is lawful to him, and therefore lawful for that he is an Apostle. For with that he began, “Am I not free? Am I not an Apostle?” and proves himself to be an Apostle, saying, “Have I not seen Christ Jesus our Lord?
Are you not my work in the Lord?” Which being proved, he shows that to be lawful to him which was so to the other Apostles; that is, that he should not work with his hands, but live by the Gospel, as the Lord appointed, which in what follows he has most openly demonstrated; for to this end did also faithful women which had earthly substance go with them, and minister unto them of their substance, that they might lack none of those things which pertain to the necessities of this life.
Which thing blessed Paul demonstrates to be lawful indeed unto himself, as also the other Apostles did it, but that he had not chosen to use this power he afterwards mentions. This thing some not understanding, have interpreted not “a woman which is a sister,” when he said, “Have we not power to lead about a sister a woman;” but, “a sister a wife.” They were misled by the ambiguity of the Greek word, because both “wife” and “woman” is expressed in Greek by the same word. Though indeed the Apostle has so put this that they ought not to have made this mistake; for that he neither says “a woman” merely, but “a sister woman;” nor “to take” (as in marriage), but “to take about” (as on a journey).
Howbeit other interpreters have not been misled by this ambiguity, and they have interpreted “woman” not “wife.”
Source: On the Work of Monks (New Advent)