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

عن عبد الله بن عباسٍ رضي الله عنهما قال: بلغَ عمرَ رضي الله عنه أن فلانًا باعَ خمرًا. فقال: قاتلَ الله فلانًا! ألم يعلم أن رسولَ الله صلى الله عليه وسلم قال: "قاتلَ الله اليهودَ، حُرِّمت عليهم الشُّحومُ، فجَمَلُوها، فباعُوها".
[صحيح] - [متفق عليه]

‘Abdullāh ibn ‘Abbās (may Allah be pleased with him) reported: ‘Umar (may Allah be pleased with him) was once informed that so-and-so sold alcohol. ‘Umar said: "May Allah destroy so-and-so! Does he not know that the Messenger (may Allah's peace and blessings be upon him) said: ‘May Allah destroy the Jews; the fat of animals was forbidden for them, but they melted it and sold it'?"
[Authentic hadith] - [Narrated by Bukhari & Muslim]

Explanation

‘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.