The effectual fervent prayer of a righteous man availeth much. – James 5:16

Prayer is the shadow of the decrees of the Eternal. God has willed such a thing, and He makes His saints to will it, and express their will in prayer. It is written, “Delight thyself also in the Lord; and He shall give thee the desires of thine heart.” It is not said that He will give the desire of his heart to every Jack and Tom; but you must first delight in the Lord, and when your mind finds all her joy in God then it is clear that God and you, as far as it can be, are standing on the same plane and moving in the same direction, and now you shall have the desire of your heart because the desire of your heart is the desire of God’s heart. Character, as much as faith, lies at the basis of prevalence in prayer. I do not mean in the case of the prayer of the sinner when he is seeking mercy, but I mean in the habitual prayers of the godly. There are some men who cannot pray so as to prevail, for sin has made them weak, and God walks contrary to them because they walk contrary to Him. He who has lost the light of God’s countenance has also lost much of the prevalence of his prayers. You do not suppose that every Israelite could have gone to the top of Carmel and opened the windows of heaven as Elijah did. No, he must first be Elijah, for it is the effectual, fervent prayer, not of every man, but of a righteous man, that availeth much; and when the Lord has put your heart and my heart into an agreement with Him then we shall pray and prevail. What did our Lord say, “If ye abide in Me, and My words abide in you, ye shall ask what ye will, and it shall be done unto you.” ~ C.H. Spurgeon

https://www.blueletterbible.org/Comm/spurgeon_charles/sermons/1469.cfm