John Chrysostom

"And Jesus came and touched them, and said, Arise, and be not afraid. And when they lifted up their eyes, they saw no man, save Jesus only." But that the fear abiding so long might not drive out their recollection, presently He puts an end to their alarm, and is seen Himself alone, and commands them to tell no man this, until He is risen from the dead.

Homily on the Gospel of Matthew 56 ↗

Theophylact of Ohrid

And Jesus came and touched them, and said, Arise, and be not afraid. Lest the fear grip them for a long time and obliterate the memory of what they had seen, the Lord rouses them and reassures them.

Commentary on Matthew ↗

Jerome

And Jesus came and touched them. Because they were lying down and unable to rise, he kindly approached and touched them, so that fear would flee with the touch and their weakened limbs would be strengthened. And he said to them: Rise up, and do not be afraid. He who healed with his hand, heals with his command. Do not be afraid. First, fear is expelled, so that later, knowledge may be given.

Commentary on Matthew ↗

Thomas Aquinas

Then Christ's strengthening is presented. And he strengthens them by deed and by word: by deed, against fear and against falling; against fear, by his presence, because Jesus came. Psalm 22:4: I will fear no evils, for you are with me. And above at 14:27: it is I, be not afraid. Likewise he strengthens by touch, because he gives power to the faint, Isaiah 40:29, and in Daniel it is read: his hand touched me and raised me up; hence it says and he touched them. Likewise he strengthens against falling; hence, and he said to them: arise. …

Commentary on Matthew ↗