זוהר בראשית — דף קסט ע”ב

The Zohar describes the spirits and harmful beings that were given a place because of the diminished moon; they are appointed over desolate places and wildernesses. The unclean spirit comes from the serpent and leads people astray, as it led Adam astray. One who comes to defile himself draws it to himself, while one who comes to purify himself finds it subdued. According to the text, “No evil shall befall you” refers to Lilith, and “plague” to the other harmful beings. Rabbi Elazar warns against going out alone at night, and describes spirits that cling to a sleeping person and give birth to harmful beings. Rabbi Shimon, from Balaam who “went alone,” teaches that one who walks alone draws an unclean spirit; hence a lifeless body is not left overnight.