'Fast' in the Bible

“Thus says the Lord of hosts, ‘The fast of the fourth [month to mourn the breaching of Jerusalem’s walls], the fast of the fifth [month to mourn the temple’s destruction], the fast of the seventh [month to mourn Gedaliah’s assassination], and the fast of the tenth [month to mourn the siege of Jerusalem] will become times of joy and gladness and cheerful feasts for the house of Judah; so [to bring this about] love truth and peace.’