What does the Bible say about praying too much?

I don't understand how these verses: > "Do not be quick with your mouth, do not be hasty in your heart to utter anything before God. God is in heaven and you are on earth, so let your words be few." - Ecclesiastes 5:2 > > "And when you pray, do not keep on babbling like pagans, for they think they will be heard because of their many words." - Matthew 6:7 Can be reconciled with Luke 18:1-8 where Jesus gives a parable about praying with persistence. Is it possible to pray too much about something? Is it possible to pray continually yet with few words? What do other parts of the bible have to say on this issue?