Bismillah irRahman irRaheem
In the Name of Allaah, The Most Gracious, The Most Kind

Jabir son of Abd Allah (RAA) reported that he heard the messenger of Allah
(SAW) say in the year of the conquest of Makka:

" Allah and His messenger prohibit the sale of alcohol, dead animals,
pigs and idols. "

Someone asked:

" Oh, messenger of Allah, what about the fat of dead animals? It can
be used to insulate ships, soften (tanned) hides, and provide light
(e.g., candles). "

The messenger of Allah (SAW) answered:

" No, this too is forbidden. " and then said:
" May Allah punish the Jews! When He made fat unlawful for them to
eat, they melted it, sold it and consumed its price. "

Al-Bukhari