Malachi 2:7 Kabbala: Or Neerav

Previous [indications] in this matter [are] that one may not study Torah except from a messenger of the Lord of Hosts (Mal. 2:7), as our rabbis, their memory be a blessing, have taught.¹Mo’ed Katan 17a: “If the master is like a ‘messenger of God,’ they should seek Torah from his mouth. If not, let them not seek Torah from his mouth.” They have also said that one should not learn from a magus.²Shabbat 75a: “He who learns one thing from a magus is worthy of death.” Besides that, there are two rules [to be followed] by those beginning in this science.