'Seventy' in the Bible

The angel of Yahweh answered and said, "O Yahweh of hosts, {how long} will you have no compassion on Jerusalem and the cities of Judah, [with] which you showed fury these seventy years?"

"Say to all the people of the land and to the priests: 'When you fasted and lamented in the fifth and seventh months for these seventy years, did you really fast for me?