The entire myth of the angels and the daughters of men in Enoch arises from Gen 6:1-4 : ‘ the sons of God came in unto the daughters of men.’ This refers not to alliances between Sethites and Cainites, but to an early Persian (?) myth to the effect that before Zoroaster’s coming demons had corrupted the earth and allied themselves with women .
The reason for the angels’ descent in the Book of Jubilees differ from those given in this chapter . There in 4 and 5 it is said that the Watchers were sent to earth by God ‘ to instruct the children of men to do judgement and uprightness,’ and that when so doing they began to lust after the daughters of men . In 1 Enoch the angels are said to have descended because of their lust, and the same reason is given in Jalkut Shim .
The Book of Jubilees has an implicit polemic against this and other statements of Enoch . In later tradition Azazel could not return to heaven because he had outstayed the seven days’ limit assigned to angelic visitants to earth .