Mark 14:39
And He went away again and prayed, saying the same words.
Matthew 6:7
And when you pray, do not use worthless repetitions like the [unconverted] Gentiles, for they think their lengthy, repetitious wording [in prayer] is more likely to be heard [by God].
Matthew 26:42-44
He [then] went away a second time and prayed, "My Father, if this [cup of suffering] cannot pass away unless I drink it [i.e., experience the suffering], [then] let what You want be done."
Luke 18:1
Then Jesus told His disciples a parable for the purpose of showing them that they should pray continually and not become discouraged.
2 Corinthians 12:8
I pled with the Lord about this matter three times, that He would remove this problem from me.