Al-Qushayrī

Author of the Risāla, the great classical handbook: a defence of Sufism against the charge of heresy, a lexicon of its technical terms, and a compendium of the lives and sayings of its early masters, arranged so an outsider could actually follow.

The manual that made the tradition teachable — and therefore portable. When Jewish pietists in Egypt and Spain read Sufi material, this is very largely the shape it reached them in.