This term for a type of killer comes from the belief that consumption of hashish occurred in their ranks
[DOC] [TLE] hashish in islam 9th to 18th century - Europe PMC [PAR] Muslim living, does not forbid explicitly the consumption of cannabis, although ... 
Hashishiyah, a term which would seem to designate users of hashish, ... vances 
and spread its consumption throughout Islamic society,4 introduc- .....