Flavius Josephus False Teacher
At the end of Chapter 2 Flavius Josephus Antiquities of the Jews says Seth built the Great Pyramid before the Flood. This is apparently the source of this false information. The Great Pyramid was built after the Flood not before. Josephus was a false teacher. "They also were the inventors of that peculiar sort of wisdom, which is concerned with the heavenly bodies, and their order. And that their inventions might not be lost before they were sufficiently known, upon Adam’s prediction that the world was to be destroyed at one time by the force of fire, and at another time by the violence and quantity of water, they made two pillars: (13) the one of brick, the other of stone: they inscribed their discoveries on them both: that in case the pillar of brick should be destroyed by the flood, the pillar of stone might remain, and exhibit those discoveries to mankind: and also inform them that there was another pillar of brick erected by them. Now this remains in the land of Si...