'Seventy' in the Bible

And this whole land shall become a waste, an astonishment; and these nations shall serve the king of Babylon seventy years.

And it shall come to pass, when seventy years are accomplished, that I will visit on the king of Babylon and on that nation, saith Jehovah, their iniquity, and on the land of the Chaldeans, and I will make it perpetual desolations.

For thus saith Jehovah: When seventy years shall be accomplished for Babylon I will visit you, and perform my good word toward you, in bringing you back to this place.