“All teachers of the Scriptures conclude that prayer is nothing else than lifting up the heart or mind to God. But if the lifting up of the heart constitutes the essence and nature of prayer, it follows that everything else which does not invite the lifting of the heart is not prayer. Therefore, singing, talking, and whistling, when devoid of the sincere uplifting of the heart, are as unlike prayer as scarecrows in the garden are unlike human beings. The essence is wanting; only the appearance and name are present.”

Luther, Martin. “An Exposition of the Lord’s Prayer for Simple Laymen” (1519) Luther’s Works Vol. 42. (Philadelphia: Fortress Press, 1969), page 25.