Matthew 26:44
And when he left them, having gone away again, he prayed a third time, saying again the same statement.
2 Corinthians 12:8
I besought the Lord thrice about this, that it might depart from me.
Daniel 9:17-19
Now therefore, O our God, hearken to the prayer of thy servant, and to his supplications, and cause thy face to shine upon thy sanctuary that is desolate, for LORD's sake.
Matthew 6:7
And while praying do not use vain repetitions as the heathen do, for they think that they will be heard by their much speaking.
Luke 18:1
And he also spoke a parable to them about it being necessary to always pray, and not to give up,