Pelagius — on Rom 15:20 (PELAGIUS'S COMMENTARY ON ROMANS)

“A man who builds on someone else's foundation is not doing anything wrong, as long as he builds with gold and such. Here Paul is referring to those false apostles who always went to converts and never to the Gentiles because they could not work miracles. Paul also shows that he had done a good job, for he both laid the foundation and also built on top of it.”