Theophylact of Ohrid

A third time Christ prays for the reasons we spoke of above. And again He comes to the disciples, but does not reproach them, although they deserved reproach, since even after the rebukes they did not strengthen themselves but gave themselves over to sleep. What then does He say? "Are you still sleeping and resting?" He says this to shame them. Since He saw that the betrayer was coming, He said to them as if to say: now is the time for sleep — sleep on, the enemy is already coming. …

Commentary on Mark ↗

Augustine of Hippo

Or else; In that it is said, that after He had spoken these words, Sleep on note, and take your rest, He added, It is enough, and then, the hour is come; behold, the Son of man is betrayed, we must understand that after saying, Sleep on now, and take your rest, our Lord remained silent for a short time, to give space for that to happen, which He had permitted; and then that He added, the hour is come; and therefore He puts in between, it is enough, that is, your rest has been long enough.

Catena Aurea by Aquinas ↗

Bede

And he came the third time, and said to them: Sleep now, and take your rest; it is enough. When he had said: Sleep now, and take your rest, and added: It is enough, and then introduced: The hour is come; behold, the Son of Man is betrayed into the hands of sinners, and so on, it is understood that, after He had said to them: Sleep and take your rest, the Lord kept silent for a while so that what He foretold might be fulfilled, and then added: Behold, the hour is at hand, or the hour has come. …

On the Gospel of Mark ↗