Truly in prayer we are granted to converse with Him, our all-gracious and life-giving God and Savior Himself.
But even here we must pray only until God the Holy Spirit descends on us in measures of His heavenly grace known to Him.
And when He deigns to visit us, we must stop praying.
I will explain this point to you through an example.
[...] Imagine that you have invited me to pay you a visit, and at your invitation I come to have a talk with you. But you continue to invite me, saying: “Come in, please. Do come in!” Then I should be obliged to think: “What is the matter with him? Is he out of his mind?”
So it is with regard to our Lord God the Holy Spirit. That is why it is said: “Be still and know that I am God; I will be exalted among the nations. I will be exalted in the earth” (Ps. 45:10).
That is, I will appear and will continue to appear to everyone who believes in Me and calls upon Me, and I will converse with him as once I conversed with Adam in Paradise, with Abraham and Jacob and other servants of Mine, with Moses and Job, and those like them.
Many explain that this stillness refers only to worldly matters; in other words, that during prayerful converse with God you must “be still” with regard to worldly affairs.
But I will tell you in the name of God that not only is it necessary to be dead to them at prayer, but when by the omnipotent power of faith and prayer our Lord God the Holy Spirit condescends to visit us, and comes to us in the plenitude of His unutterable goodness, we must be dead to prayer too.
The soul speaks and converses during prayer, but at the descent of the Holy Spirit we must remain in complete silence, in order to hear clearly and intelligibly all the words of eternal life which he will then deign to communicate.
Complete soberness of soul and spirit, and chaste purity of body is required at the same time. The same demands were made at Mount Horeb, when the Israelites were told not even to touch their wives for three days before the appearance of God on Mount Sinai.
For our God is a fire which consumes everything unclean, and no one who is defiled in body or spirit can enter into communion with Him.
Seraphim of Sarov (Orthodox Church; 1759-1833): On the Acquisition of the Holy Spirit.