Why are we taught not to repeat words in vain when we pray (Matt. 6:7)?

St. Augustine says, “Our Lord first of all cut off ‘much speaking,’ that you might not bring a multitude of words unto God, as though by your many words you would teach Him. Therefore when you pray you have need of piety, not of wordiness. ‘For your Father knows what is needful for you, before you ask Him’ [Matt. 6:8]. But lest perhaps any should say here, ‘If He knows what is needful for us, why should we use so much as a few words? Why

91 St. Augustine of Hippo Letters, Volume II (83–130) 130 (FOTC 18:388–389).

92 St. Aphraphat, Aphrahat: Demonstrations I , trans., Kuriakose Valavanolickal (Kottayam, India: St. Ephrem Ecumenical Research Institute, 2005) 4.17 : p. 92.

93 St. Augustine of Hippo Our Lord’s Sermon on the Mount 2.22.76–77 (NPNF I/6:32).

should we pray at all?’ He knows Himself; let Him then give what He knows to be needful for us. Yes, but it is His will that you should pray, that He may give to your longings, that His gifts may not be lightly esteemed; seeing He has Himself formed this longing desire in us. The words therefore which our Lord Jesus Christ has taught us in His prayer, are the rule and standard of our desires. You may not ask for anything but what is written there.”⁹⁴