Daniel 9:2-3

2in the first year of his reign, I, Daniel, understood from the books the number of years which, according to the word of the Lord to Jeremiah the prophet, must pass before the desolations [which had been] pronounced on Jerusalem would end; and it was seventy years.

3So I directed my attention to the Lord God to seek Him by prayer and supplications, with fasting, sackcloth and ashes.