Genesis 6:4-7

4There were giants in the earth in those days; and also after that, when the sons of God came in to the daughters of men, and they bore children to them, the same became mighty men who were of old, men of renown. 5And God saw that the wickedness of man was great in the earth, and that every imagination of the thoughts of his heart was only evil continually.12

6And the LORD repented that he had made man on the earth, and it grieved him at his heart. 7And the LORD said, I will destroy man whom I have created from the face of the earth; both man, and beast, and the creeping thing, and the fowls of the air; for I repent that I have made them.3