has he been mentioned in any other sacred texts?
Yes, in the Book of Jubilees and the Rabbinic literature.
Methuselah
The Book of Jubilees presents itself as "the history of the division of the days of the Law, of the events of the years, the year-weeks, and the jubilees of the world" and claims to be a revelation of God to Moses, given through the Angel of the Presence in addition to the written Law received by Moses on Mount Sinai; and, while the written Law was to be imparted to all, this was to be a secret tradition entrusted only to the saints of each generation, to Enoch, Methuselah, Noah, and Shem, then to Abraham, Isaac, Jacob, and Levi, and finally to the priests and scribes of the latter times.

Rabbinic literature states that when Noah was four hundred and eighty years old all the righteous men were dead, except Methuselah and himself, who were of immense stature as they were descended from the sons of God. At God's command they both announced that one hundred and twenty years would be given to men for repentance; if in that time they had not mended their evil ways, the earth would be destr
who lived for many years in the bible Methuselah.
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Methuselah [SEP] In other religious texts
The apocryphal Book of Enoch claims to be revelations of Enoch, transcribed by him and entrusted to be preserved for future generations by his son, Methuselah. In this book, Enoch recounts two visions he has had to Methuselah. The first is about the Genesis flood narrative, and the second chronicles the history of the world from Adam to the Last Judgment. In the latter vision, men are represented as animals - the righteous are white cattle and sheep, the sinners and enemies of Israel are black cattle and wild animals. Following his father's death in the Book of Enoch, Methuselah is designated by God as a priest, while Methuselah's grandson, Noah's brother Nir, is designated by God as his successor.