John Chrysostom

The Lord took the disciples indeed, that they might be spectators of the miracle which was coming, but He took them alone, that no others might see that they were of such little faith. Wherefore, to show that others went across separately, it is said, And there were also with him other ships. Lest again the disciples might be proud of being alone taken, He permits them to be in danger; and besides this, in order that they might learn to bear temptations manfully. …

Catena Aurea by Aquinas ↗

Theophylact of Ohrid

But so that they would not become proud because He sent the others away and took them, and at the same time, to teach them to endure dangers, He allows them to be in danger from the storm.

Commentary on Mark ↗

Bede

And a great storm of wind arose, and the waves were beating into the boat, so that the boat was already filling. And he was in the stern, asleep on the cushion. While the disciples were sailing, Christ fell asleep, because when the faithful trample the world underfoot and meditate on the peace of the future kingdom in their minds, and, whether by the favorable breath of the Holy Spirit or by the rowing of their own effort, they eagerly cast behind their backs the infidelity of worldly pride, the time of the Lord's passion suddenly …

On the Gospel of Mark ↗