Covenant References
Jeremiah 25 and 29

"seventy years"

25:1 The word that came to Jeremiah concerning all the people of Judah in the fourth year of Jehoiakim the son of Josiah king of Judah, that was the first year of Nebuchadnezzar, king of Babylon;
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25:11 And this whole land shall be a desolation, and an astonishment; and these nations shall serve the king of Babylon seventy years.

29:10 For thus saith the Lord, That after seventy years be accomplished at Babylon I will visit you, and perform my good word toward you, in causing you to return to this place.