May Allah destroy the Jews; the fat of animals was forbidden for them, but they melted it and sold it.

‘Umar ibn al-Khattāb (may Allah be pleased with him) was informed that a man used a trick: He wanted to benefit from alcohol without drinking it. So, he sold it. That was an exposed forbidden trick. Therefore, ‘Umar (may Allah be pleased with him) supplicated against the man, just as the Prophet (may Allah's peace and blessings be upon him) had done with the Jews, who resorted to similar tricks. ‘Umar said: "May Allah destroy him! Does he not know that resorting to trickery is forbidden?"

This is because it features acting deceitfully towards Allah and His Messenger. The Prophet (may Allah's peace and blessings be upon him) said: "May Allah destroy the Jews," because when Allah prohibited them from consuming animal fat, they sought to benefit from it by means of a trick. They transformed its nature by melting it and then sold it and consumed its price. They claimed that they did not actually eat the fat that was forbidden to them.

They think that they deceive Allah, but He is deceiving them.