Sefer ha-Shem, Heikhal ha-Shem, 30a.

Jewish Mysticism
[The term] ‘atarah is [related to words] “encompassing” (heqqef) and “surrounding” (sibbuv), as it says, “O Lord, You encompass him (ta‘terennu) with favor like a shield” (Ps. 5-13). The ‘atarah encircles the head as well, and thus she encircles everything that emanates from her, and she also rises to the “head of Your true word” (ibid. 119-160) through the power of the crown (keter) and of the mercy (hesed) that is within her. The corona of circumcision (‘ateret ha-milah) in the arc of the penis alludes to this ‘atarah, and in the arc is the form of a waw and in the corona the form of a yod, the “glorious crown” (‘ateret tif’eret).

Translated by Elliot Wolfson in, “Coronation of the Sabbath Bride- Kabbalistic Myth and the Ritual of Androgynisation,” Journal of Jewish Thought and Philosophy 6 (1997)- 301-344.