Albert Barnes Commentary Romans 15:18

"For I will not dare to speak of any things save those which Christ wrought through me, for the obedience of the Gentiles, by word and deed," — Romans 15:18 (ASV)

For I will not dare to speak. I should be restrained; I should be afraid to speak, if the matter were not as I have stated. I should be afraid to set up a claim beyond what is strictly in accordance with the truth.

Which Christ hath not wrought by me. I confine myself strictly to what I have done. I do not arrogate to myself what Christ has done by others. I do not exaggerate my own success, or claim what others have accomplished.

To make the Gentiles obedient. To bring them to obey God in the gospel.

By word and deed. By preaching, and by all other means; by miracle, by example, etc. The deeds, that is, the lives of Christian ministers are often as efficacious in bringing me to Christ as their public ministry.