Behar: The Sabbatical and Jubilee Years

[We are all one] by virtue of the source of [our] souls in the One G-d; only the bodies are separated. Thus, for those who give major consideration to their bodies while regarding their souls as of secondary importance, there can be no true love and brotherhood among them, but only [a love] which is dependent on a [transitory] thing. This is what Hillel the Elder meant when he said in regard to the fulfillment of this commandment [--love of one's fellow], "This is the entire Torah; the rest is but commentary... " For the basis and root of the entire Torah is to raise and exalt the soul high above the body, reaching unto the Source and Root of all the worlds.

  –Tanya, chapter 32