Then the Lord said, "My spirit shall not abide in mortals forever, for they are flesh; their days shall be one hundred twenty years."
References for Genesis 6:3
The Nephilim were on the earth in those days—and also afterward—when the sons of God went in to the daughters of humans, who bore children to them. These were the heroes that were of old, warriors of renown.
The Lord saw that the wickedness of humankind was great in the earth, and that every inclination of the thoughts of their hearts was only evil continually.
And the Lord was sorry that he had made humankind on the earth, and it grieved him to his heart.
So the Lord said, "I will blot out from the earth the human beings I have created—people together with animals and creeping things and birds of the air, for I am sorry that I have made them."
But Noah found favor in the sight of the Lord.
These are the descendants of Noah. Noah was a righteous man, blameless in his generation; Noah walked with God.
And Noah had three sons, Shem, Ham, and Japheth.
Now the earth was corrupt in God's sight, and the earth was filled with violence.
And God saw that the earth was corrupt; for all flesh had corrupted its ways upon the earth.
And God said to Noah, "I have determined to make an end of all flesh, for the earth is filled with violence because of them; now I am going to destroy them along with the earth.