Of Prayer, by John Calvin, tr. Henry Beveridge , at sacred-texts.com
If, with minds thus framed to obedience, we allow ourselves to be governed by the laws of Divine Providence, we shall easily learn to persevere in prayer, and suspending our own desires wait patiently for the Lord, certain, however little the appearance of it may be, that he is always present with us, and will in his own time show how very far he was from turning a deaf ear to prayers, though to the eyes of men they may seem to be disregarded. This will be a very present consolation, if at any time God does not grant an immediate answer to our prayers, preventing us from fainting or giving way to despondency, as those are wont to do who, in invoking God, are so borne away by their own fervour, that unless he yield on their first importunity and give present help, they immediately imagine that he is angry and offended with them and abandoning all hope of success cease from prayer. On the contrary, deferring our hope with well tempered equanimity, let us insist with that perseverance which is so strongly recommended to us in Scripture. We may often see in The Psalms how David and other believers, after they are almost weary of praying, and seem to have been beating the air by addressing a God who would not hear, yet cease not to pray because due authority is not given to the word of God, unless the faith placed in it is superior to all events. Again, let us not tempt God, and by wearying him with our importunity provoke his anger against us. Many have a practice of formally bargaining with God on certain conditions, and, as if he were the servant of their lust, binding him to certain stipulations; with which if he do not immediately comply, they are indignant and fretful, murmur, complain, and make a noise. Thus offended, he often in his anger grants to such persons what in mercy he kindly denies to others. Of this we have a proof in the children of Israel, for whom it had been better not to have been heard by the Lord, than to swallow his indignation with their flesh (Num. 11:18, 33).