Translated by W. Curtis.
But this, too, God graciously gives through Christ who said to His disciples: "No longer do I call you servants, because the servant knows not what his lord's will is, but I have called you friends, because all the things that I have heard from my Father I have made known to you; so that through Christ there is made known to them the will of one who, when He teaches them the will of the Lord, has no desire to be their lord any longer but instead becomes a friend to those whose lord he was before." Moreover, as no one knows the things of man save the Spirit of man that is in him, so also no one knows the things of God save the Spirit of God.
Now if no one knows the things of God save the Spirit of God, it is impossible that a man should know the things of God. But mark how this too becomes possible: but we, he says, have received not the spirit of the world but the spirit which is from God, that we may know the things graciously given to us by God, and these also we speak not in words taught of human wisdom but in those taught of the Spirit. But I think, right pious and industrious Ambrosius, and right discreet and manful Tatiana, from whom I avow that womanly weakness has disappeared as truly as it had from Sarah of old, you are wondering to what purpose all this has been said in preface about things impossible for man becoming possible by the grace of God, when the subject prescribed for our discourse is Prayer.
The fact is, I believe it to be itself one of those things which, judged by our weakness, are impossible, clearly to set forth with accuracy and reverence a complete account of prayer, and in particular of how prayer ought to be offered, what ought to be said to God in prayer, which seasons are more, which less, suitable for prayer . . . The very apostle who by reason of the abundance of the revelations is anxious that no one should account to him more than he sees or hears from him, confesses that he knows not how to pray as he ought, for what we ought to pray, he says, we know not how to as we ought. It is necessary not merely to pray but also to pray as we ought and to pray what we ought. For even though we are enabled to understand what we ought to pray, that is not adequate if we do not add to it the right manner also.
Reference address : https://www.ellopos.net/elpenor/greek-texts/fathers/origen/prayer.asp?pg=2