זוהר בראשית — דף רלב ע”א

When Jacob was buried in the Cave of Makhpelah, all the patriarchs were reunited together. The cave is the burial place of the patriarchs. The secret is that the Cave of Makhpelah corresponds to the lower Garden of Eden. Whoever is buried there ascends to the supernal Garden of Eden. All the patriarchs in the cave are united as one, connected to the supernal worlds.