Merkabah mysticism (Hebrew, “Charior” mysticism) is the Jewish on God’s Throne; later the Jewish speculation on Ezekiel’s vision of God’s chariot.
Still later such a study was recognized as dangerous for untutored minds in the Babylonian Talmud, merkaabah mysticism was described as a major subject while rabbinic casuistry was assessed as minor. Fragments of merkabah mysticism were found among the Dead Sea Scrolls and in the rabbinic midrash.
Johanan ben Zakkai was a practitioner of merkabah mysticism and his accounts closely resembled the account of Saul/Paul Damascus road experience (with the obvious exception of the perception of Jesus) that it seemed virtually certain that Saul was an adept in merkabah mysticism which spread to the Christian Gnostics. They preserved the tradition, which later the Kabbalaists adopted.
Bowker, John, The Oxford Dictionary of World Religions, New York, Oxford University Press, 1997, p. 656