10. this continued . . . two years--in addition to the former three months. See on Ac 20:31. But during some part of this period he must have paid a second unrecorded visit to Corinth, since the one next recorded (see on Ac 20:2, 3) is twice called his third visit (2Co 12:14; 13:1). See on 2Co 1:15, 16, which might seem inconsistent with this. The passage across was quite a short one (see on Ac 18:19) --Towards the close of this long stay at Ephesus, as we learn from 1Co 16:8, he wrote his FIRST EPISTLE TO THE CORINTHIANS; also (though on this opinions are divided) the EPISTLE TO THE GALATIANS. (See Introduction to First Corinthians, and Introduction to Galatians). And just as at Corinth his greatest success was after his withdrawal to a separate place of meeting (Ac 18:7-10), so at Ephesus.
      so that all they which dwelt in--the Roman province of
      Asia heard the word of the Lord Jesus, both Jews and Greeks--This is the "great door and effectual opened unto him" while resident at Ephesus (1Co 16:9), which induced him to make it his headquarters for so long a period. The unwearied and varied character of his labors here are best seen in his own subsequent address to the elders of Ephesus (Ac 20:17, &c.). And thus Ephesus became the "ecclesiastical center for the entire region, as indeed it remained for a very long period" [BAUMGARTEN]. Churches arose at Colosse, Laodicea, and Hierapolis eastward, either through his own labors or those of his faithful helpers whom he sent out in different directions, Epaphras, Archippus, Philemon (Col 1:7; 4:12-17; Phm 23).

JFB.