But it is to be known, that, as ofttimes the faith of him that draweth near to receive supplies the miraculous virtue, so ofttimes the power of those that work the miracle is sufficient even without the faith of those who sought to receive. Cornelius and his household, by their faith, attracted to them the grace of the Holy Spirit [Acts 10:4]; but the dead man who was cast into the sepulchre was revived solely by virtue of the holy body. [2 Ki 13:21]
It happened that the disciples were then weak in faith; for indeed they were but in an imperfect condition before the cross; wherefore He here tells them, that faith is the mean of miracles, “Verily I say unto you, if ye shall have faith as a grain of mustard-seed, ye shall say to this mountain, Remove hence, and it shall remove.”
Reproduced in full. Translation: Oxford 1841 (Newman), public domain (Public domain).