If God were to answer all prayers the instant they were uttered, He would become an automaton, the power link in a clever bit of magic.  He would not be the God who wisely responds to His people, and who disposes of all things according to His sovereign goodness, but a powerful genie constrained by a magic bottle called prayer.

D. A. Carson, A Call to Spiritual Reformation (Grand Rapids: Baker Books, 1992), 116-117.