2. How this comfort must be obtained and fetched in—by prayer (v. 3): Call upon me, and I will answer them. The prophet, having received some intimations of this kind, must be humbly earnest with God for further discoveries of his kind intentions. He had prayed (ch. xxxii. 16), but he must pray again. Note, Those that expect to receive comforts from God must continue instant in prayer. We must call upon him, and then he will answer us. Christ himself must ask, and it shall be given him, Ps. ii. 8. I will show thee great and mighty things (give thee a clear and full prospect of them), hidden things, which, though in part discovered already, yet thou knowest not, thou canst not understand or give credit to. Or this may refer not only to the prediction of these things which Jeremiah, if he desire it, shall be favoured with, but to the performance of the things themselves which the people of God, encouraged by this prediction, must pray for. Note, Promises are given, not to supersede, but to quicken and encourage prayer. See Ezek. xxxvi. 37.