זוהר בראשית — דף צו ע”א

The Zohar explains the verse “Let me sing for my beloved” as referring to Isaac, who was called beloved even before he came into the world. It examines the addition of the heh to Abraham and Sarah: Abraham rose through the upper heh and Sarah descended through the lower heh; the two hehs joined and brought forth above the yod, the first letter of Isaac. Isaac begot above, and Jacob completed everything. It then mentions the view that the beloved is Abraham, and explains “my beloved’s song about his vineyard” as the Holy One, blessed be He, and “on a horn, a son of oil” as the horn of the jubilee and the anointing oil that kindles the lights, by which David’s kingship was anointed. It ends on the words “He fenced it and cleared it of stones.”