But without faith it is impossible to please Him: for he that cometh to God must believe that He is, and that He is a rewarder of them that diligently seek Him. – Hebrews 11:6

You cannot be instant in prayer, nay, you cannot offer an acceptable prayer at all except as you believe in the prayer-hearing God. The modern wise men assure us, with a patronizing air, that prayer is a pious exercise, exceedingly beneficial to ourselves, but quite inoperative with God. They are kind enough to allow us to pray, only we must not suppose that it has the slightest effect. And do they think that we are such idiots that we would stand and whistle to the wind and find good for our souls in such a stupid proceeding? They must have formed their notion of our mental condition from their own if they imagine that we should pray if we knew that God did not hear us, and would not answer us. Prayer apart from the idea of a hearing God is not praying; it is soliloquizing, or, in plainer words, a silly talking to yourself, such as one sees in half-witted old persons who have outlived what few senses they once possessed. You must believe that God is, and that your pleadings are a part of the divine way of blessing you, or else you are not praying but maundering and chattering. The Lord does really listen to the pleadings of His people, and though He does not alter His ordinance and His decree, yet in some way or other He makes the prayers of His people to be an efficient link in the machinery of His providence and grace, so that not without prayer doth He bless them, but with it He doth bless them abundantly. Dear friends, may the Lord the Holy Spirit stir us all up to be instant in mighty, energetic prayer. ~ C.H. Spurgeon

https://www.blueletterbible.org/Comm/spurgeon_charles/sermons/1480.cfm