The Book of the Cave of Treasures 24
1And when Lamech had lived seven hundred and seventy years, he died during the lifetime of Methuselah, his father, forty years before the Flood, on the twenty-first day of the month of Tlal (September), on the first day of the week (Sunday), in the sixty-eighth year of the life of Shem, the firstborn of Noah. And Noah his firstborn embalmed him, and Methuselah his father swathed him for burial, and they buried him in the Cave of Treasures, and mourned for him forty days.