Then shall ye call upon me, and ye shall go and pray unto me, and I will hearken unto you.

Jamieson-Fausset-Brown Bible Commentary

12. Fulfilled (Da 9:3, &c.). When God designs mercy, He puts it into the hearts of His people to pray for the mercy designed. When such a spirit of prayer is poured out, it is a sure sign of coming mercy.

go-to the temple and other places of prayer: contrasted with their previous sloth as to going to seek God.

Matthew Henry's Concise Commentary

29:8-19 Let men beware how they call those prophets whom they choose after their own fancies, and how they consider their fancies and dreams to be revelations from God. False prophets flatter people in their sins, because they love to be flattered; and they speak smoothly to their prophets, that their prophets may speak smoothly to them. God promises that they should return after seventy years were accomplished. By this it appears, that the seventy years of the captivity are not to be reckoned from the last captivity, but the first. It will be the bringing to pass of God's good word to them. This shall form God's purposes. We often do not know our own minds, but the Lord is never at an uncertainty. We are sometimes ready to fear that God's designs are all against us; but as to his own people, even that which seems evil, is for good. He will give them, not the expectations of their fears, or the expectations of their fancies, but the expectations of their faith; the end he has promised, which will be the best for them. When the Lord pours out an especial spirit of prayer, it is a good sign that he is coming toward us in mercy. Promises are given to quicken and encourage prayer. He never said, Seek ye me in vain. Those who remained at Jerusalem would be utterly destroyed, notwithstanding what the false prophets said to the contrary. The reason has often been given, and it justifies the eternal ruin of impenitent sinners; Because they have not hearkened to my words; I called, but they refused.