Heroin and al-Khui

The name of the book “Sairatun najat fi ajvibatul istiftaat” by Abul Kasim Al Khui

Question #1286: Is it permissible to cultivate heroin and tiriyeq (type of drugs), if we take into consideration that it possible to gain some benefit from it?
Answer: If there wouldn’t be any harm, this couldn’t be prohibited.