John Chrysostom

And He enumerates each thing that was to happen to Him; lest if He should pass any thing over, they should be troubled afterwards at suddenly seing it; wherefore he adds, Behold, we go up to Jerusalem, and the Son of Man.

Catena Aurea by Aquinas ↗

Theophylact of Ohrid

Why does Jesus predict to the disciples what will happen to Him? To strengthen their spirit, so that having heard about it beforehand, they would bear it courageously when it came to pass, and not be struck by its suddenness; and at the same time they were to know that He suffers of His own will. For he who foresaw the sufferings could have avoided them, and if he did not flee, it is clear that he voluntarily gives himself over to suffering. …

Commentary on Mark ↗

Gregory the Dialogist

Our Redeemer, foreseeing that the souls of the disciples would be troubled by His passion, foretold to them long beforehand both the suffering of that same passion and the glory of His resurrection, so that when they saw Him dying, as had been predicted, they would not doubt that He would also rise again. But because the disciples, still carnal, were by no means able to grasp the words of the mystery, a miracle is performed. …

Forty Gospel Homilies, Homily 2 ↗

Bede

And taking the twelve again, he began to tell them what was going to happen to him. 'Behold, we are going up to Jerusalem, and the Son of Man will be delivered to the chief priests and the scribes, and they will condemn him to death, and will deliver him to the Gentiles, and they will mock him, and will spit on him, and will scourge him, and will kill him, and after three days he will rise again.' Our Redeemer, foreseeing that his passion would disturb the spirits of his disciples, foretold to them both the penalty of his passion and …

On the Gospel of Mark ↗