Genesis 6:1-4

WHEN MEN began to multiply on the face of the land and daughters were born to them, The sons of God saw that the daughters of men were fair, and they took wives of all they desired and chose. Then the Lord said, My Spirit shall not forever dwell and strive with man, for he also is flesh; but his days shall yet be 120 years. There were giants on the earth in those days–and also afterward–when the sons of God lived with the daughters of men, and they bore children to them. These were the mighty men who were of old, men of renown.