Kabbalah zu Jeschijahu 22:12

"And on that day Hashem Tzva'ot called to weeping, to mourning, to baldness, and to girding with sackcloth" (Yeshayah 22:12). This means that only on that day, when the Temple was destroyed (did He call). But aside from that day, there is no greater joy for the Holy One blessed be He, than when the wicked of the world, who provoke Him, are removed from this world. As it is written: "And when the wicked perish there is joy" (Mishlei 11:10). So in each generation, when judgment is executed on wicked people, there is joy and songs before the Holy one, blessed be He.