John Chrysostom

"By faith, they passed through the Red Sea as by dry land." Again he compares one whole people with another, lest they should say, we cannot be as the saints. "By faith" (he says) "they passed through the Red Sea, as by dry land, which the Egyptians assaying to do, were drowned." Here he leads them also to a recollection of the sufferings in Egypt. How, "by faith"? Because they had hoped to pass through the sea, and therefore they prayed: or rather it was Moses who prayed. …

Homily on Hebrews 27 ↗

Theophylact of Ohrid

Lest they say: why do you put forward inimitable men? he brought the people as an example too. Imitate, he says, at least those from the crowd who believed that the water would not drown them, and so took courage, hoping in God, that they would pass "through the midst of the sea on dry ground" (Ex. 14:21–22); thus, faith makes the impossible possible. Why then do you not believe? And no one, he says, can say that it was an illusion, that there was no water. …

Commentary on Hebrews ↗

Oecumenius

"By faith they passed through the Red Sea." Indeed, they believed that they would pass through, and they did pass through. Such is the power of faith, that it makes possible even those things that are impossible. "but the Egyptians, when they attempted to do the same." For perhaps they suspected that the sea was land, and they also tried to pass through, but their destruction showed that it was truly the sea, and not some kind of illusion. …

The Pseudo-Oecumenian Catena on Hebrews ↗

Thomas Aquinas

623. – Then (v. 29) he shows what he did in the very passing: first, he shows this; secondly, he shows that this pertained to faith (v. 30b). He says, therefore, by faith they passed through the Red Sea, as by dry land. Two things were done there by faith: one was what the men did, namely, they committed themselves to cross over; and this was done only by faith. The other was on God's part, namely, that the waters acted as a wall for them. …

Commentary on Hebrews ↗