His name through faith in his name. — We have, in technical language, the efficient cause distinguished from the indispensable condition of its action. The Name did not work as a formula of incantation; it required, on the part both of the worker and the receiver, faith in that which the Name represented, the manifestation of the Father through the Son.
Hath made this man strong. — The verb is the same as that which had been used in Acts 3:7 of the “feet and ankle-bones.” It was Jesus who had given them that new firmness.
The faith which is by him. — The causation of the miracle is carried yet another step backward. The faith which was alike in the healer and in the man healed was itself wrought in each by the power of Christ. The man was first a willing recipient of that faith spiritually, and then was in a state that made him worthy to be a recipient also of the bodily restoration.
This perfect soundness. — Literally, this completeness. This is the only passage in the New Testament in which the word occurs. The cognate adjective is found in the “whole” of 1 Thessalonians 5:23; the “complete” of James 1:4.