Zechariah 8:19

Thus saith 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, special days of fasting and affliction which the Jews had observed during their captivity in memory of certain dark days in the history of their nation, Cf Zechariah 7:3, shall be to the house of Judah joy and gladness and cheerful feasts, festivals of highest happiness, since the Lord intended to pour out upon them such a multitude of blessings as to make them forget all the disagreeable facts in their past history and to rejoice in the goodness and mercy of their God; therefore love the truth and peace, this reaction on the part of the Jews being a necessary consequence of their appreciation of the Lord's goodness and mercy.