John Chrysostom

"What then," saith one, "if the leper's opinion was mistaken?" It were meet to do away with it, and to reprove, and set it right. Did He then so do? By no means; but quite on the contrary, He establishes and confirms what had been said. For this cause, you see, neither did He say, "Be thou cleansed," but, "I will, be thou clean;" that the doctrine might no longer be a thing of the other's surmising, but of His own approval. But the apostles not so: rather in what way? …

Homily on the Gospel of Matthew 25 ↗

Theophylact of Ohrid

"And Jesus put forth His hand, and touched him, saying, I will it; be thou clean. And immediately his leprosy was cleansed. And Jesus saith unto him, See thou tell no man; but go thy way, show thyself to the priest, and offer the gift that Moses commanded, for a testimony unto them." He touches the leper to show that He is not subject to the law which forbids one to touch a leper, but rather that He is Master of that law. He also shows that for Him Who is pure, nothing is impure, and that His holy flesh imparts holiness. …

Commentary on Matthew ↗

John Damascene

For He was not only God, but man also, whence He wrought Divine wonders by touch and word; for as by an instrument so by His body the Divine acts were done.

Catena Aurea by Aquinas ↗

Jerome

And Jesus, extending His hand, touched him, saying: I will, be clean. And immediately his leprosy was cleansed. By extending His hand, the Lord caused the leprosy to flee. Consider also how humble and devoid of boasting His response is. The man had said, if you will: the Lord answered, I will. The man had said, you can cleanse me: The Lord unites and says, be cleansed. …

Commentary on Matthew ↗

Thomas Aquinas

Then he describes the help; first, he heals; secondly, he gives an instruction. First, the deed; secondly, the effect (v. 3b). Christ does three things in the curing: He stretches out his hand, when he gives help: "Put forth your hand from on high and rescue me" (Ps 144:7). …

Commentary on Matthew ↗