“And when you pray, do not use vain repetitions as the heathen do. For they think that they will be heard for their many words.”
Listen to the "Verse by Verse" episode covering this scripture.
God does not give us prayers to memorize and repeat mindlessly as a ritual. He is not interested in babble and hearing certain syllables intoned repetitiously, as it seems the pagans believed their “gods” did. He wants His followers to “avoid meaningless, repetitive prayers offered under the misconception that mere length will make prayers efficacious” (Zondervan NIV Bible Commentary on Matthew 6:7-8).
God is interested in us having an actual conversation with Him, listening to what He says in the Bible and sharing our thoughts, requests, cares and praise with Him in a focused and meaningful way. Repeating someone else’s words over and over again can’t help but become rote and ritual rather than building the relationship God desires.