John Calvin Commentary Matthew 26:43

"And he came again and found them sleeping, for their eyes were heavy." — Matthew 26:43 (ASV)

And found them sleeping again. This drowsiness arose neither from excessive eating and drinking, nor from gross stupidity, nor even from weak indulgence of the flesh, but rather—as Luke tells us—from immoderate sorrow.

Therefore, we perceive more clearly how strong the tendency of our flesh is to indifference, since even dangers lead us to forgetfulness of God. Thus, on every side, Satan finds suitable and ready opportunities for spreading his snares for us.

For if we dread no danger, he intoxicates and drowns us in sleep; and if we experience fear and sorrow, which ought to arouse us to pray, he overwhelms our senses so that they do not rise to God. Thus, in every respect, men fall away and forsake God, until he restores them.

We must also observe this point: that the disciples, after having been sharply reproved, fell asleep again almost at that very moment. Nor is this said of the whole group, but of the three whom Christ had selected to be his chief companions. And what shall we say of the greater number, when this happened to the choicest of them?

Now, the repetition of the same words was not a vain repetition, (βατταλογία) which Christ formerly condemned in hypocrites, Matthew 6:7, who hope that they will obtain by idle talking what they do not ask honestly and sincerely.²⁰⁹

But Christ intended to show by his example that we must not be discouraged or grow weary in praying if we do not immediately obtain our wishes. So then, it is not a superfluous repetition of the words if a repulse we have experienced is so far from extinguishing the ardor of prayer that we ask a third and fourth time what God appears to have denied.

²⁰⁹ Harmony, vol. 1, p. 313