Mark 14:39

And again he went away and prayed, saying the same words.

But when ye pray, use not vain repetitions, as the heathen do; for they think that they shall be heard for the multitude of their words.

Again he went away a second time, and prayed, saying, My Father, if this [cup] cannot pass away from me, but I must drink it, thy will be done!

And he spoke a parable to them to show that they ought to pray always, and not be fainthearted:

In respect to this I besought the Lord thrice, that it might depart from me;

Treasury of Scripture Knowledge

And again he went away, and prayed, and spake the same words.

But when ye pray, use not vain repetitions, as the heathen do; for they think that they shall be heard for the multitude of their words.

Again he went away a second time, and prayed, saying, My Father, if this [cup] cannot pass away from me, but I must drink it, thy will be done!

And he spoke a parable to them to show that they ought to pray always, and not be fainthearted:

In respect to this I besought the Lord thrice, that it might depart from me;