"The Arabic (and now international) word "hashish" also acquired a new meaning at the time of the Crusades.
A twelfth-century sect of hashish users who lived in the area of the Golan Heights and who were in the habit of toking up before they set out on secret missions to assassinate their various enemies came to be known as hashshashin. Hence the word 'assassin'"
Source "Ten Thousand Lovers" a novel by Edeet Ravel. Copyright 2003 by Edeet Ravel. First USA publication by Perennial Books (Harper Collins) 2003