The Lord would do a wonderful work in the hearts of the exiles, helping them to recognize (literally know) the Lord as a personal God (1 Chronicles 28:9; Psalms 9:10; 36:10; Isaiah 19:21; 52:6; Daniel 11:32; Hosea 2:20; Titus 1:16; 1 John 4:6–8).
They will be My people, and I will be their God: God’s covenant with Israel would become a personal reality for them (Exodus 6:7; 19:5; Deuteronomy 29:13; Revelation 21:7).
all their heart: The exiles would not mix religious loyalties; they would be fully committed to the one true God.