Luke 11:1

And that he might point out the kind of teaching, the disciple proceeds, as John also taught his disciples. Of whom in truth thou hast told us, that among them that are born of women there had arisen none greater than he. And because thou hast commanded us to seek things that are great and eternal, whence shall we arrive at the knowledge of these but from Thee, our God and Saviour?

The disciples having seen a new way of life, desire a new form of prayer, since there were several prayers to be found in the Old Testament. Hence it follows, When he ceased, one of his disciples said to him, Lord, teach us to pray, in order that we might not sin against God in asking for one thing instead of another, or by approaching God in prayer in a manner that we ought not.

(Orat. Dom. Serm. 1.) He unfolds the teaching of prayer to His disciples, who wisely desire the knowledge of prayer, directing them how they ought to beseech God to hear them.

Now whereas He possesses every good in abundance, why does He pray, since He is full, and has altogether need of nothing? To this we answer, that it befits Him, according to the manner of His dispensation in the flesh, to follow human observances at the time convenient for them. For if He eats and drinks, He rightly was used to pray, that He might teach us not to be lukewarm in this duty, but to be the more diligent and earnest in our prayers.

After the account of the sisters, who signified the two lives of the Church, our Lord is not without reason related to have both Himself prayed, and taught His disciples to pray, seeing that the prayer which He taught contains in itself the mystery of each life, and the perfection of the lives themselves is to be obtained not by our own strength, but by prayer. Hence it is said, And it came to pass, that, as he was praying in a certain place.