3 So the Lord said, “My Spirit will not remain in humankind indefinitely, since they are mortal. They will remain for 120 more years.” 4 The Nephilim were on the earth in those days (and also after this) when the sons of God would sleep with the daughters of humankind, who gave birth to their children. They were the mighty heroes of old, the famous men. 5 But the Lord saw that the wickedness of humankind had become great on the earth. Every inclination of the thoughts of their minds was only evil all the time.
1 And it came to pass when the children of men began to multiply on the face of the earth and daughters were born unto them, that the angels of God saw them on a certain year of this jubilee, that they were beautiful to look upon; and they took themselves wives of all whom they chose, and they bare unto them sons and they were giants. 2 And lawlessness increased on the earth and all flesh corrupted its way, alike men and cattle and beasts and birds and everything that walks on the earth -all of them corrupted their ways and their orders, and they began to devour each other, and lawlessness increased on the earth and every imagination of the thoughts of all men (was) thus evil continually.
Notes and References
"... In common with other Second Temple sources, (Some of the details in Jubilees 5 are strikingly reminiscent of the flood account in 1 Enoch 10-11) Jubilees assumes that the proximate cause of the food was the mating of the “sons of God” with the daughters of men in Genesis 6:1-4. These “sons of God” are, for Jubilees and other interpreters, the angels of the Lord. Te ofspring born of their union with humans were giants. The identification of these offspring, who are referred to as Nephilim in Genesis 6:4, as “giants” derives from an entirely separate biblical passage, Numbers 13:32-33, wherein some beings “of great stature” are also called Nephilim. Putting these two passages together, ancient interpreters understood the Nephilim in Genesis 6:4 likewise to be of great stature, the giants who resulted from the mating of angels with humans ..."
Kugel, James L. A Walk through Jubilees: Studies in the Book of Jubilees and the World of Its Creation (p. 52) Brill, 2012