All the knowledge in the kabbalah.Where does it come from?
- Is it parts of the talmud?
- From the Torah?
- People who have been in heaven?
- Personal revelation?
Where and how did they receive this knowledge?
According to Aruch Hashulchan seen here siff 8, it was given at sinai to Moshe.
פשיטא שגם אגדה וקבלה ניתנה למשה מסיני ומקרו תורה
My translation: It is obvious that Agadah and Kabbalah were also given to Moshe from Sinai and its source is Torah .