What does the Bible say about praying too much?

I agree that the bible encourages constant prayer! Prayer is so, so important to increase your spiritual maturity and growth! When the bible says not to pray like the pagans is is because the pagans would just babble and believed the lengthier the prayer the more 'strength', the prayer had in a way. Even prayer in brevity can move mountains.

If I were to say: Depart from me satan in The name of JESUS!

You can bet that the lord is there!

Now the actual answer to your question is directly answered in 1 Thess. 5:17:

17 Pray without ceasing.

That is very frank. This doesn't mean for all eternity and every second of the day, for not even Jesus prayed every second of the day, but rather that you should pray everyday (daily), not just for your meals, and before bed, but always! Even if it's just to give a shout of praise to the Lord Almighty! Pray in perseverance, make your requests known to God, pray until you get an answer!

Well, that's a very good question. Bible contains several verses to understand how often should we pray, how long should our prayers be, etc...

Let's consider on a first hand Matthew 26:41 :

Keep on the watch and pray continually, so that you may not enter into temptation.

On first reading, one might think we might always pray, that's it : continually. This could be confirmed by Romans 12:12 and even 1 Thessalonians 5:17, that encourage us to "persevere in prayer" and "pray incessantly". Other reference are Ephesians 6:18

However, these statements do not mean that we must be praying God every moment of the day ! Rather, the Bible is urging us to pray regularly, continually thanking God for his goodness to us, looking for his guidance, comfort and strength. Indeed, if we truly appreciate the privilege of prayer, we will find many opportunities to pray our heavenly Father.

But of course, we should use this privilege with wisdom, as there are several conditions for prayers to be accepted by God. So we may pray for anything that is in harmony with God's will, as we can read in 1 John 5:14 :

And this is the confidence that we have toward him, that no matter what we ask according to his will, he hears us.

But, as this topic(What may we pray for ?) could be covered in an entire post, just remember we can't pray for anything.

So, if we need to talk to God, ask him something according to his will, He will ALWAYS listen. There is no limit, no quota, when it comes to speak with our heavenly Father !

If you read a little beyond vs2 in Ecl 5 you'll find this:

4 When thou vowest a vow unto God, defer not to pay it; for he hath no pleasure in fools: pay that which thou hast vowed. 5 Better is it that thou shouldest not vow, than that thou shouldest vow and not pay

This is the reason for vs 2. Don't hastily make a promise to God. You may find yourself unable or unwilling to honor that promise.

The Bible in no place says that you can possibly pray too much. In fact, it says just the opposite. Not only in the passage in Luke, but also in 1 Thessalonialns 5:17, which says we should be praying continually.

Like most "contradictions' this one is simple to resolve by showing that the problem arises from taking verses out of context. (See Rules behind resolving alleged Biblical discrepancies.)

Take a look again at Ecclesiastes 5 with the surrounding verses:

1 Guard your steps when you go to the house of God. To draw near to listen is better than to offer the sacrifice of fools, for they do not know that they are doing evil. 2 [b] 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 are on earth. Therefore let your words be few. 3 For a dream comes with much business, and a fool's voice with many words.

4 When you vow a vow to God, do not delay paying it, for he has no pleasure in fools. Pay what you vow. 5 It is better that you should not vow than that you should vow and not pay. 6 Let not your mouth lead you[c] into sin, and do not say before the messenger[d] that it was a mistake. Why should God be angry at your voice and destroy the work of your hands? 7 For when dreams increase and words grow many, there is vanity;[e] but[f] God is the one you must fear.

This is not talking about not praying, it's talking about not speaking rashly and carelessly to God.

This is backed up by most commentaries. Here's a small sampling to show that this is an established teaching/understanding of the verses, and not just my opinion:

Benson Commentary

Be not rash with thy mouth — Speak not without due consideration; and let not thy heart be hasty — Do not give way to every sudden motion of thy heart, nor suffer it to break out of thy lips till thou hast well weighed it. We must think, and think twice, before we speak, when we are to speak, either from God in preaching, or to God in prayer, or in solemn vows and promises made in his presence; which were very much in use in those times, and of which he speaks in the following verses. For God is in heaven — Is a God of infinite majesty, holiness, and knowledge, and therefore not even to be thought of, and much more not to be worshipped, without profound veneration, great solemnity, and much serious consideration; and thou upon earth — Thou art a poor worm of the earth, infinitely below him, and therefore oughtest to stand in awe of him, and fear to offend him; therefore let thy words be few — 1st, In prayer: use not vain repetitions, nor a multitude of words, as if they were necessary to inform God of thy wants, or to prevail with him to grant thy requests; or as if thou shouldest certainly be heard upon that very account: see Matthew 6:7. 2d, In vowing: be not too prodigal in making more vows and promises than thou art either able or willing and resolved to perform. Remember that God looks down from heaven, hears all thy vows, and expects a punctual accomplishment of them.

Matthew Henry's Concise Commentary

5:1-3 Address thyself to the worship of God, and take time to compose thyself for it. Keep thy thoughts from roving and wandering...

Gill's Exposition of the Entire Bible

Be not rash with thy mouth, and let not thine heart be hasty to utter any thing before God,....