Part 13 · Chapter 144

And the reason for the matter is that "hair" (se'ar) are the letters of "ten" (eser), and it is the aspect of the Mochin of Gadlut, which are the Names of YHVH in their fillings, each of which has ten letters within it, being Ab (72), Sag (63), Mah (45), Ban (52). Also "hair" (se'ar) is the letters of "ten" (eser), in the secret of the Yod, the first letter of the Name YHVH.