ASV notes on Genesis 5:25-32
Methuselah became the oldest man that ever lived; he lived in the blessing of his father Enoch and became 969 years. Methuselah had Lamech the father of Noah who was to continue the mankind on earth after the flood. Lamech the father of Noah didn’t become 900 years or more, no he died at the age of 777, God saved him from the flood, Lamech died just a few years before the flood came.
In verse 29, Lamech said that his son Noah would bring them rest and comfort from all the hard work with the soil that the LORD cursed. Lamech is calling God YAHAWAH; this was the common name on God from the beginning. Lamech talking about rest and comfort is a prophesy of the coming of Jesus.
Noah also walked with God like Enoch did and preached to family, friends and all around him. God denied the wife of Noah, children until Noah was 500 years then they had Shem Ham and Japheth. The sin had a devastating effect on people and the society, but God protected the children of Noah by him having children late in life and soon they were occupied by building a huge box to float on water.