Cross reference
Matthew 26:44
44 And he left them again, and went away, and prayed a third time, saying again the same words.
2 Corinthians 12:8
8 Concerning this thing I besought the Lord thrice, that it might depart from me.
Daniel 9:17-19
17 Now therefore, O our God, hearken unto the prayer of thy servant, and to his supplications, and cause thy face to shine upon thy sanctuary that is desolate, for the Lord's sake.
18 O my God, incline thine ear, and hear; open thine eyes, and behold our desolations, and the city which is called by thy name: for we do not present our supplications before thee for our righteousness, but for thy great mercies' sake.
19 O Lord, hear; O Lord, forgive; O Lord, hearken and do; defer not, for thine own sake, O my God, because thy city and thy people are called by thy name.
Matthew 6:7
7 And in praying use not vain repetitions, as the Gentiles do: for they think that they shall be heard for their much speaking.
Luke 18:1
1 And he spake a parable unto them to the end that they ought always to pray, and not to faint;