But God hath revealed them unto us by His Spirit: for the Spirit searcheth all things, yea, the deep things of God. -1 Corinthians 2:9

Ordinary closet prayer will only make ordinary Christians of us. It is in extraordinary seasons, when we are led by God to devote, say an hour, to earnest prayer; when we feel an impulse, we scarce know why, to cut off a portion of our time during the day to go alone. Then, beloved, we kneel down, and begin to pray in earnest. It may be that we are attacked by the devil; for when the enemy knows we are going to have a great blessing, he always makes a great noise to drive us away; but if we keep at it, we shall soon get into a quiet frame of mind, and hear him roaring at a distance. Presently you get hold of the Angel, and say, “Lord, I will not let Thee go, except Thou bless me.” He asks your name. You begin to tell him what your name was:

“Once a sinner, near despair,
Sought Thy mercy-seat by prayer;
Mercy heard and set him free;
Lord, that mercy came to me.”

You say, “What is Thy name, Lord?” He will not tell you. You hold Him fast still; at last He deigns to bless you. That is certainly some foretaste of heaven, when you feel alone with Jesus. Let no man know your prayers; they are between God and yourselves; but if you want to know much of heaven, spend some extra time in prayer; for God then reveals it to us by His Spirit. ~ C.H. Spurgeon

https://www.blueletterbible.org/Comm/spurgeon_charles/sermons/0056.cfm