The Jews have suffered numerous and terrible persecutions including the Spanish inquisition, the Russian pogroms and the Nazi Holocaust. The Bible predicted that this is exactly what would happen.
For example, Deuteronomy says that if the people of Israel did not serve God as he had commanded then . . .
And you shall become a horror, a proverb, and a byword among all the peoples where the Lord will lead you away. (Deut 28:37)
“And the Lord will scatter you among all peoples, from one end of the earth to the other, and there you shall serve other gods of wood and stone, which neither you nor your fathers have known. And among these nations you shall find no respite, and there shall be no resting place for the sole of your foot, but the Lord will give you there a trembling heart and failing eyes and a languishing soul. Your life shall hang in doubt before you. Night and day you shall be in dread and have no assurance of your life. In the morning you shall say, ‘If only it were evening!’ and at evening you shall say, ‘If only it were morning!’ because of the dread that your heart shall feel, and the sights that your eyes shall see. (Deut 28:64-67)
This is a sad but accurate prophecy of the holocaust.
Similarly, the prophet Jeremiah wrote
Behold, I am sending for many fishers, declares the Lord, and they shall catch them. And afterward I will send for many hunters, and they shall hunt them from every mountain and every hill, and out of the clefts of the rocks.
This passage makes it clear that the purpose of the persecution was to drive the Jews back to Israel, which is exactly what happened after WW2.
However, just because the persecution was predicted doesn’t mean it gave God any pleasure. In fact his prophets have written elsewhere “for he who touches you [Israel] touches the apple of his eye” (Zec 2:8).