Zech. 8:19 Thus says the LORD of hosts: The fast of the fourth month, and the fast of the fifth, and the fast of the seventh, and the fast of the tenth, shall be seasons of joy and gladness, and cheerful festivals for the house of Judah: therefore love truth and peace.
The people of God had been fasting the days in which they commemorated the fateful events in the life of Israel. The "fast of the fourth month" was to remind Israel that Nebuchadnezzar had entered Jerusalem in 586 B.C. The fast of the fifth month "commemorated the burning of the Temple and other buildings in 586. The seventh remembered Gedaliah’s assassination. The tenth recalled the beginning of the siege of Jerusalem in 588 (2 Kings 25:1)." (Ryrie) When Israel is restored all of this will change. Fasting will become feasting in a period of time when the people love truth and peace.
When would truth come? Jesus said, "I am the way, the truth, and the life…