Genesis 6:1-3

1Now it happened, when men began to multiply on the face of the land, and daughters were born to them,

2that the sons of God saw that the daughters of men were beautiful and desirable; and they took wives for themselves, whomever they chose and desired.

3Then the Lord said, “My Spirit shall not strive and remain with man forever, because he is indeed flesh [sinful, corrupt—given over to sensual appetites]; nevertheless his days shall yet be a hundred and twenty years.”