12 And Kenan was seventy years old when he became the father of Mahalalel: 13 And after the birth of Mahalalel, Kenan went on living for eight hundred and forty years, and had sons and daughters: 14 And all the years of Kenan's life were nine hundred and ten; and he came to his end. 15 And Mahalalel was sixty-five years old when he became the father of Jared: 16 And after the birth of Jared, Mahalalel went on living for eight hundred and thirty years, and had sons and daughters: 17 And all the years of Mahalalel's life were eight hundred and ninety-five: and he came to his end.
Matthew Henry's Commentary on Genesis 5:12-17
Commentary on Genesis 5:6-20
(Read Genesis 5:6-20)
Concerning each of these, except Enoch, it is said, "and he died." It is well to observe the deaths of others. They all lived very long; not one of them died till he had seen almost eight hundred years, and some of them lived much longer; a great while for an immortal soul to be prisoned in a house of clay. The present life surely was not to them such a burden as it commonly is now, else they would have been weary of it. Nor was the future life so clearly revealed then, as it now under the gospel, else they would have been urgent to remove to it. All the patriarchs that lived before the flood, except Noah, were born before Adam died. From him they might receive a full account of the creation, the fall, the promise, and the Divine precepts about religious worship and a religious life. Thus God kept up in his church the knowledge of his will.