זוהר בראשית — דף קלג ע”ב

The Zohar lists the four wives of each patriarch and explains that Keturah is Hagar, who changed her deeds and her name. On “Abraham took again,” Abraham did not enter Sarah’s tent, which was left to Isaac, and “Abraham gave all that he had to Isaac” is read as Sarah’s likeness in that dwelling and as the secret of fire and water. The gifts to the sons of the concubines denote lower ranks on the side of impurity; Abraham sent them eastward, away from Isaac, where, according to the text, the sides of sorcery are found, and from where Laban, Beor and Balaam came. Rabbi Hizkiyah opens with “Who gave Jacob over to plunder?”: since the destruction of the Temple, blessings are withheld, and the lower ranks rule over Israel because of its sins.