John Calvin Commentary Acts 9:16

"for I will show him how many things he must suffer for my name`s sake." — Acts 9:16 (ASV)

And because. Paul could not do this and have Satan remain quiet, and the world yield to him willingly; therefore Luke adds that he will also be taught to bear the cross. For the meaning of the words is, I will accustom him to suffer troubles: to endure reproaches, and to endure all manner of conflicts, so that nothing may terrify him and keep him from doing his duty.

And when Christ makes himself Paul’s teacher in this matter, he teaches that the more every person has profited in his school, the more able he is to bear the cross. For we strive against it and refuse it as a most contrary thing, until he makes our minds more gentle.

This passage also teaches that no one is fit to preach the gospel, since the world is set against it, except for one who is armed to suffer. Therefore, if we are to show ourselves faithful ministers of Christ, we must not only earnestly ask from his hand the spirit of knowledge and wisdom, but also of constancy and strength, so that we may never be discouraged by laboring and toiling; which is the condition of the godly.