זוהר בראשית — דף קיז ע”ב

Rabbi Yose continues: this calculation is found in the book of Rav Yeiva the Elder; “then the land shall be appeased” and “I will remember My covenant with Jacob” belong to the secret of the “vav.” Everything is hidden before the Holy One, blessed be He, and lies in the secret of the letters of the Name; the remembrance of Sarah too was in the secret of the “vav.” How long must one remain in exile? Everything depends on repentance: “I will hasten it in its time” — if they merit it, I will hasten it; if not, in its time. On the road Rabbi Yose recalls that his father told him that at the age of sixty he would find in that place a treasure of supernal wisdom. He entered a cave, found a book lodged in a crevice of the rock, and left with it.