The following is from Father Augustine’s (d. 430 A.D) commentary on The Lord’s Sermon on the Mount, book II, chapter 3.
10.And when you pray,says He,you shall not be as the hypocrites are; for they love to pray standing in the synagogues and in the corners of the streets, that they may be seen of men.And here also it is not the being seen of men that is wrong, but doing these things for the purpose of being seen of men; and it is superfluous to make the same remark so often, since there is just one rule to be kept, from which we learn that what we should dread and avoid is not that men know these things, but that they be done with this intent, that the fruit of pleasing men should be sought after in them. Our Lord Himself, too, preserves the same words, when He adds similarly,Verily I say unto you, They have received their reward;hereby showing that He forbids this—the striving after that reward in which fools delight when they are praised by men.
11.But when you pray,says He,enter into your bed-chambers.What are those bed-chambers but just our hearts themselves, as is meant also in the Psalm, when it is said,What ye say in your hearts, have remorse for even in your beds?And when you have shut the doors,says He,pray to your Father who is in secret.It is a small matter to enter into our bed-chambers if the door stand open to the unmannerly, through which the things that are outside profanely rush in and assail our inner man. Now we have said that outside are all temporal and visible things, which make their way through the door, i.e. through the fleshly sense into our thoughts, and clamorously interrupt those who are praying by a crowd of vain phantoms. Hence the door is to be shut, i.e. the fleshly sense is to be resisted, so that spiritual prayer may be directed to the Father, which is done in the inmost heart, where prayer is offered to the Father which is in secret.And your Father,says He,who sees in secret, shall reward you.And this had to be wound up with a closing statement of such a kind; for here at the present stage the admonition is not that we should pray, but as to how we should pray. Nor is what goes before an admonition that we should give alms, but as to the spirit in which we should do so, inasmuch as He is giving instructions with regard to the cleansing of the heart, which nothing cleanses but the undivided and single-minded striving after eternal life from the pure love of wisdom alone.
12.But when you pray,says He,do not speak much, as the heathen do; for they think that they shall be heard for their much speaking.As it is characteristic of the hypocrites to exhibit themselves to be gazed at when praying, and their fruit is to please men, so it is characteristic of the heathen, i.e. of the Gentiles, to think they are heard for their much speaking. And in reality, every kind of much speaking comes from the Gentiles, who make it their endeavour to exercise the tongue rather than to cleanse the heart. And this kind of useless exertion they endeavour to transfer even to the influencing of God by prayer, supposing that the Judge, just like man, is brought over by words to a certain way of thinking.Therefore, be not like them,says the only true Master.For your Father knows what things are necessary for you, before you ask Him.For if many words are made use of with the intent that one who is ignorant may be instructed and taught, what need is there of them for Him who knows all things, to whom all things which exist, by the very fact of their existence, speak, and show themselves as having been brought into existence; and those things which are future do not remain concealed from His knowledge and wisdom, in which both those things which are past, and those things which will yet come to pass, are all present and cannot pass away?
13. But since, however few they may be, yet there are words which He Himself also is about to speak, by which He would teach us to pray; it may be asked why even these few words are necessary for Him who knows all things before they take place, and is acquainted, as has been said, with what is necessary for us before we ask Him? Here, in the first place, the answer is, that we ought to urge our case with God, in order to obtain what we wish, not by words, but by the ideas which we cherish in our mind, and by the direction of our thought, with pure love and sincere desire; but that our Lord has taught us the very ideas in words, that by committing them to memory we may recollect those ideas at the time we pray.
14. But again, it may be asked (whether we are to pray in ideas or in words) what need there is for prayer itself, if God already knows what is necessary for us; unless it be that the very effort involved in prayer calms and purifies our heart, and makes it more capacious for receiving the divine gifts, which are poured into us spiritually. For it is not on account of the urgency of our prayers that God hears us, who is always ready to give us His light, not of a material kind, but that which is intellectual and spiritual: but we are not always ready to receive, since we are inclined towards other things, and are involved in darkness through our desire for temporal things. Hence there is brought about in prayer a turning of the heart to Him, who is ever ready to give, if we will but take what He has given; and in the very act of turning there is effected a purging of the inner eye, inasmuch as those things of a temporal kind which were desired are excluded, so that the vision of the pure heart may be able to bear the pure light, divinely shining, without any setting or change: and not only to bear it, but also to remain in it; not merely without annoyance, but also with ineffable joy, in which a life truly and sincerely blessed is perfected.