And He fulfilled what He previously promised so that we who by His sanctification have received the Spirit and truth, may also by His teaching worship truly and spiritually.
For what can be a more spiritual prayer than that which was given to us by Christ, by whom also the Holy Spirit was given to us?
What praying to the Father can be more truthful than that which was delivered to us by the Son who is the Truth, out of His own mouth?
[...] Let us therefore, brethren beloved, pray as God our Teacher has taught us.
It is a loving and friendly prayer to beseech God with His own word, to come up to His ears in the prayer of Christ.
Let the Father acknowledge the words of His Son when we make our prayer, and let Him also who dwells within in our breast Himself dwell in our voice.
And since we have Him as an Advocate with the Father for our sins, let us, when as sinners we petition on behalf of our sins, put forward the words of our Advocate.
For since He says, that “whatsoever we shall ask of the Father in His name, He will give us” (John 16:23), how much more effectually do we obtain what we ask in Christ’s name, if we ask for it in His own prayer!
[...] Moreover, in His teaching the Lord has bidden us to pray in secret – in hidden and remote places, in our very bed-chambers.
This is best suited to faith, that we may know that God is everywhere present, and hears and sees all, and in the plenitude of His majesty penetrates even into hidden and secret places.
[...] And when we meet together with the brethren in one place, and celebrate divine sacrifices with God’s priest, we ought to be mindful of modesty and discipline.
We are not to throw abroad our prayers indiscriminately, with unsubdued voices, nor to cast to God with tumultuous wordiness a petition that ought to be commended to God by modesty.
For God is the hearer, not of the voice, but of the heart.
Nor need He be clamorously reminded, since He sees men’s thoughts, as the Lord proves to us when He says “Why think ye evil in your hearts?” (Matt. 9:4).
And in another place: “And all the churches shall know that I am He that searcheth the hearts and reins” (Apoc. 2:23).
Cyprian of Carthage (d.258): On The Lord’s Prayer, 2-4.