One of the earliest cabalists. According to an account which is not altogether trustworthy, he was the real founder of cabalistic science; its secrets are said to have been revealed to him in a vision by the prophet Elijah. These Isaac transmitted to Jacob Nazir, who taught them to Abraham b. David, the latter in turn entrusting them to his son Isaac the Blind.
- Azulai, Shem ha-Gedolim, s.v. RABaD the Second.