Martin Luther, again, this time, on prayer

....Take note that a prayer is not good and right because of its length, devoutness, sweetness, or its plea for temporal or eternal goods. Only that prayer is acceptable which breathes a firm confidence and trust that it will be heard (no matter how small and unworthy it may be in itself) because of the reliable pledge and promise of God. Not your zeal but God’s Word and promise render your prayer good. This faith, based on God’s words, is also the true worship; without it all other worship is sheer deception and error.  -- Martin Luther