They did not say: Lord, teach us how to pray, but : "Lord teach us to pray." A great many people know how to pray but they do not pray. The request: Teach us how to pray, would refer simply to the theory. The petition "Teach us to pray," is of much fuller import, and includes theory and practice.
G. Campbell Morgan, The Practice of Prayer
“He who prays aright with his heart will not much err with foot and hand and head.”
"An ounce of Mary's prayer is worth more than a ton of Martha's work.”