Matthew Poole and continuators on 1 Corinthians 16:9

9 For a great door and effectual is opened to me , and there are many adversaries .

For God hath opened to me at Ephesus a great opportunity to preach the Gospel, which I have reason to hope will also be effectual for the Conversion of many Souls. What this door of hope was, whether God had let him know there were many Souls in that place prepared for receiving the Gospel; or that some eminent Persons for Authority or Learning, whom many were like to follow, were there already converted; or that he looked upon that famous City as like to be a place where many might be converted, is not told us.

And (saith the Apostle) there are many Adversaries, (as it will appear to those that read Acts 19, & 20.) therefore there was need of the presence of the Apostle himself, whose Authority might better stop their mouths, than the more inferior Pastors could. What would have affrighted others from going or staying there, this great Apostle mentions as an Argument to cause him to make haste to go thither, and to tarry there for some time.

Marginal references: Acts 14.27. 2 Cor. 2.12.