1 Enoch 6:2
1 And it came to pass when the population of humans had increased during those times, beautiful and attractive daughters were born to them. 2 And the angels, the children of heaven, saw them and desired them, and said to each other: 'Come, let us choose wives from among the humans and father children.' 3 And Semjâzâ, their leader, said to them: 'I fear that you will not actually agree to do this, and I alone will have to pay the penalty of a great sin.' 4 And they all replied to him and said: 'Let us all take an oath, and all bind ourselves with a solemn promise not to abandon this plan but to carry out this act.' 5 Then they all took an oath together and bound themselves with a solemn promise to do so.
Tertullian On the Apparel of Women 1.3
I am aware that the Scripture of Enoch, which has assigned this order (of action) to angels, is not received by some, because it is not admitted into the Jewish canon either. I suppose they did not think that, having been published before the deluge, it could have safely survived that world-wide calamity, the abolisher of all things. If that is the reason (for rejecting it), let them recall to their memory that Noah, the survivor of the deluge, was the great-grandson of Enoch himself; and he, of course, had heard and remembered, from domestic renown and hereditary tradition, concerning his own great-grandfather"s grace in the sight of God, and concerning all his preachings; since Enoch had given no other charge to Methuselah than that he should hand on the knowledge of them to his posterity.
Notes and References
"... Tertullian mentions 1 Enoch 15 in On the Apparel of Women 1.2; 1.3. In 1.2 Tertullian speaks at length of ornaments and makeup on women being traced back to the fallen angels' dealing with women in The Book of the Watchers. He mentions 'those angels, to wit, who rushed from heaven on the daughters of men.' and then says that they taught the women about metallurgy and eye makeup and jewelry (from the metallurgy). Because the angels were ill masters, they taught lustful things. He then interprets the Watchers story to his own means saying, 'women who possessed angels (as husbands) could desire nothing more;' but that they became worse for their lusts. Tertullian then said that men would judge angels because of the actions of the Watchers. There is a fair bit that could be said about Tertullian's feelings on makeup or his interpretive skills and methods, but what is important here for this thesis is that Tertullian used the Watcher story as an actual event to support his own thesis. In On the Apparel of Women 1.3 Tertullian defended the genuineness of the prophecy of Enoch ..."
Vanbeek, Lawrence H. The Letter of Jude's Use of 1 Enoch: The Book of the Watchers as Scripture (pp. 151-153) University of South Africa, 1997