1 Corinthians 16:5

5.When I shall pass through Macedonia The common opinion is, that this espistle was sent from Philippi. Persons coming thence to Corinth by land, required to pass through Macedonia; for that colony is situated in the farthest extremity, towards the Emathian mountains. Paul, it is true, might, instead of going by land, have gone thither by sea, but he was desirous to visit the Macedonian Churches, that he might confirm them in passing. So much for the common opinion. To me, however, it appears more probable, that the epistle was written at Ephesus; for he says a little afterwards, that he will remain there until Pentecost, (1 Corinthians 16:8) (156); and he salutes the Corinthians, not in the name of the Philippians, but of the Asiatics. (1 Corinthians 16:19.) (157) Besides, in the second epistle he explicitly states, that, after he had sent away this epistle, he passed over into Macedonia. (2 Corinthians 2:13.) Now after passing through Macedonia, he would be at a distance from Ephesus, and in the neighborhood of Achaia. Hence I have no doubt that he was at Ephesus at that time: thence he could sail by a straight course to Achaia. For visiting Macedonia, a long circuit was needed, and a more disagreeable route. Accordingly he lets them know that he will not come to them by a direct course, as he required to go through Macedonia

To the Corinthians, however, he promises something farther — that he would make a longer stay with them By this he shows his affection towards them. For what reason had he for delay, except that he was concerned as to their welfare? On the other hand, he lets them know how fully assured he is of their affection towards him in return, by taking it, as it were, for granted that he would be conducted forward by them in the way of kindness; for he says this from confidence in their friendship. (158)

After saying everything, however, he subjoins this limitation —if the Lord permit With this reservation, saints ought to follow up all their plans and deliberations; for it is an instance of great rashness to undertake and determine many things for the future, while we have not even a moment in our power. The main thing indeed is, that, in the inward affection of the mind, we submit to God and his providence, whatever we resolve upon; (159) but at the same time, it is becoming that we should accustom ourselves to such forms of expression, that whenever we have to do with what is future we may make everything depend on the divine will. (160)