The Shariah forbids all intoxicants. A Moslem who drinks wine or uses hashish acts against the Shariah, but someone who uses an intoxicant for spiritual purposes can rightly be called not just a sinner but a heretic.
Nevertheless a great many people in Iran, Afghanistan, Pakistan, India and elsewhere use preparations of cannabis for various spiritual reasons. Very little has been published on this subject, and of that little almost nothing of value. Between 1968 and 1978 I had occasion to observe and participate in such hemp use, and I consider my own observations of some small value.