Matthew 6:7
"But when ye pray, use not vain repetitions, as the heathen do: for they think that they shall be heard for their much speaking."
Cross References (ranked by relevance)
For in the multitude of dreams and many words there are also divers vanities: but fear thou God.
(For after all these things do the Gentiles seek:) for your heavenly Father knoweth that ye have need of all these things.
And he left them, and went away again, and prayed the third time, saying the same words.
He went away again the second time, and prayed, saying, O my Father, if this cup may not pass away from me, except I drink it, thy will be done.
But when they knew that he was a Jew, all with one voice about the space of two hours cried out, Great is Diana of the Ephesians.
And he went a little farther, and fell on his face, and prayed, saying, O my Father, if it be possible, let this cup pass from me: nevertheless not as I will, but as thou wilt.