And indeed we must seek the true rule of prayer in the word of God, that we may not rashly break through to Him, but may approach him in the manner in which he has revealed himself to us. This appears more clearly from the adjoining context, where Jacob, recalling the command and promise of God to memory, is supported as by two pillars. Certainly the legitimate method of praying is, that the faithful should answer to God who calls them; and thus there is such a mutual agreement between his word and their vows, that no sweeter and more harmonious symphony can be imagined. “O Lord,” he says, “I return at thy command: thou also didst promise protection to me returning; it is therefore right that thou shouldest become the guide of my journey.” This is a holy boldness, when, having discharged our duty according to God’s calling, we familiarly ask of him whatsoever he has promised; since he, by binding himself gratuitously to us, becomes in a sense voluntarily our debtor. But whoever, relying on no command or promise of God, offers his prayers, does nothing but cast vain and empty words into the air.
John Calvin, Commentaries, 23 Vols
genesis, prayer, worship