'Seventy Years' in the Bible

Then the Angel of the Lord said, “O Lord of hosts, how long will You withhold mercy and compassion from Jerusalem and the cities of Judah, against which You have had indignation and anger these seventy years [of the Babylonian captivity]?”

“Speak to all the people of the land and to the priests, saying, ‘When you fasted and mourned in the fifth and seventh months these seventy years [that you were in exile], was it actually for Me that you fasted?