Methuselah lived after he fathered Lamech 782 years and had other sons and daughters.
Concerning Methuselah observe, 1. The signification of his name, which some think was prophetical, his father Enoch being a prophet. Methuselah signifies, he dies, or there is a dart, or, a sending forth, namely, of the deluge, which came the very year that Methuselah died. If indeed his name was so intended and so explained, it was fair warning to a careless world, a long time before the judgment came.
Commenting on Genesis 5:25-27
Lamech--a different person from the one mentioned in the preceding chapter [Gen 4:18]. Like his namesake, however, he also spoke in numbers on occasion of the birth of Noah--that is, "rest" or "comfort" [Gen 5:29, Margin]. "The allusion is, undoubtedly, to the penal consequences of the fall in earthly toils and sufferings, and to the hope of a Deliverer, excited by the promise made to Eve.
Gen 5:3-32 As Adam was created in the image of God, so did he beget “in his own likeness, after his image;” that is to say, he transmitted the image of God in which he was created, not in the purity in which it came direct from God, but in the form given to it by his own self-determination, modified and corrupted by sin.
Commenting on Genesis 5:3-32