When Moses renewed the Lord’s covenant with Israel at Mount Horeb, he foresaw, in Deuteronomy 4:25–31, that they would turn away from the Lord and they would be driven out of the land to live among a foreign people. But their unfaithfulness would not mean the end of the Lord’s covenant faithfulness. He told them that they will seek the Lord your God and you will find him, if you search after him with all your heart and with all your soul.
Even while in tribulation
they will return to the Lord and obey his voice. All of this would happen because the Lord is a merciful God
and "he will not leave you or destroy you or forget the covenant with your fathers that he swore to them” (Deuteronomy 4:30–31). These words from the covenant loom large as the Lord says to the exiles in Babylon that the future hope he has promised them includes their calling on him in prayer, seeking him with all their hearts and finding him. This wholehearted commitment to the Lord is unlikely to be something that will only come about some time in the future when the people return to the land. The context and the covenant background make it much more likely that this turning to the Lord will begin to take place even while the exiles are in Babylon. The Lord will in fact use the experience of being in Babylon for seventy years to bring about a change of heart in his people. Ultimately, the exile will be instrumental in restoring their covenant relationship with the Lord and he will bring them back from the place which I sent you into exile.
This all takes place because despite the unfaithfulness of his people, the Lord will always remain faithful to his covenant promises (Deuteronomy 4:30–31).
12 Then you will call upon me and come and pray to me, and I will hear you.