Jamieson, Fausset and Brown on Romans 15:18-22

18-22. For I will not dare to speak of any--"to speak aught"

of those things which Christ hath not wrought by me--a modest, though somewhat obscure form of expression, meaning, "I will not dare to go beyond what Christ hath wrought by me"--in which form accordingly the rest of the passage is expressed. Observe here how Paul ascribes all the success of his labors to the activity of the living Redeemer, working in and by him.

by word and deed--by preaching and working; which latter he explains in the next clause.