According to the Shari?ah, it is not permissible to use Marijuana. (Shaami vol.3 pg.239; HM Saeed)
Ummi Salma [Radhiallaahu anhu] reports that Rasulullah [Sallallaahu Alayhi Wasallam] has prohibit
ted every intoxicant and everything which causes weakness to the body. (Ahmad Hadith26513)
In Mirqaat, it is mentioned that once a person came to Cairo and requested the Ulama to provide proof for Marijuana being Haraam. A gathering of the Ulama was conducted in order to address the issue. Hafiz Zainud-deen al-Iraqi (RA) presented the aforementioned Hadith as the proof and this was accepted by those present.
Imaam ibn Taymiyah (RA) and Imaam Iraqi (RA) have mentioned that there is Ijmaa (consensus) that Marijuana is Haraam. (Awnul Ma?bood vol.6 pg.509; Darul Hadith)
and Allah Ta’ala Knows Best
Mufti Ebrahim Desai