"And in praying do not heap up empty phrases as the Gentiles do; for they think that they will be heard for their many words... " -- Matthew 6:7 RSV
This injunction, amongst other things, seems to be against redundancy in prayer. It may be echoing something Solomon said in Ecclesiastes
Be not rash with your mouth, nor let your heart be hasty to utter a word before God, for God is in heaven, and you upon earth; therefore let your words be few. -- Ecclesiastes 5:2 RSV
And we are good at redundancy. How many times have I prayed, "Lord, please be with so-and-so." How redundant is that! What meaningless babble! Doesn't Matthew 28:20 say, "Lo, I am with you always, even to the end of the age"? Why ask God to do what he's already been doing for thousands of years?