“The transition from the usual meaning of the word Kabbalah to the esoteric nuance was easily made. We find the first sign of it in Yehudah ben Barzilai. Speaking of the creation of the Holy Spirit, which is the Shekhinah, he says: “The sages did not deal with it at length, in order that men would not come to form ideas concerning ‘what is above,’ etc. and that is why they were accustomed to transmitting this thing in whispers and in secret, as a tradition to their pupils and to the sages.”
The ordinary expression “to transmit something as Kabbalah [orally]” here acquires through the addition of the adverbs “in whispers and in secret” the quality of an esoteric tradition. Somewhat similar is the use of the term in an Arabic text of 1223 that counters Maimonides in its assertion that where the Kabbalah of the sages of Israel is mentioned the reference is to the baraithoth of the Hekhaloth literature as the true interpretation of Ma’aseh Merkabah (A. Harkavy, in his appendix Hadashim gam Yeshanim to the Hebrew translation of Graetz’s Geschichte 5:47).
But contrary to Harkavy’s view, this passage in no way proves that the term Kabbalah in its novel, technical sense was known in the Orient in 1223. That, precisely, is Kabbalah, in the sense of the Provençal school. But Eleazar of Worms also cites traditions of this kind—for example, with respect to the names of the angels—as “Kabbalah.” Besides, still other expressions were used in Isaac’s circle. In a letter sent to Gerona, Isaac himself speaks in this sense of hokhmah, wisdom or science, without adding the adjective penimith, “esoteric,” although this often occurs in other places.
In the twelfth century, the expression of sefarim penimiyyim appears in France for writings considered there as esoteric literature, such as Seder ‘Eliyahu Zutta.
In the liturgical manual Sefer ha-Manhig, composed in 1204 by Abraham ben Nathan ha-Yarhi of Lunel, who in his youth had studied with the Rabad, the “Greater Hekhaloth” are twice designated by this term.”
Gershom Scholem, Origins of the Kabbalah, pp. 261-3.