Genesis 6:3-5

3Then the Lord said, “My Spirit will not put up with humans for such a long time, for they are only mortal flesh. In the future, their normal lifespan will be no more than 120 years.”

4In those days, and for some time after, giant Nephilites lived on the earth, for whenever the sons of God had intercourse with women, they gave birth to children who became the heroes and famous warriors of ancient times.

5The Lord observed the extent of human wickedness on the earth, and he saw that everything they thought or imagined was consistently and totally evil.