'Seventy' in the Bible

All this land will be a waste and a cause of wonder; and these nations will be the servants of the king of Babylon for seventy years.

And it will come about, after seventy years are ended, that I will send punishment on the king of Babylon, and on that nation, says the Lord, for their evil-doing, and on the land of the Chaldaeans; and I will make it a waste for ever.

For this is what the Lord has said: When seventy years are ended for Babylon, I will have pity on you and give effect to my good purpose for you, causing you to come back to this place.