1 Enoch 6:2

1 And it came to pass when the children of men had multiplied that in those days were born unto them beautiful and comely daughters. 2 And the angels, the children of the heaven, saw and lusted after them, and said to one another: 'Come, let us choose us wives from among the children of men and beget us children.' 3 And Semjâzâ, who was their leader, said unto them: 'I fear ye will not indeed agree to do this deed, and I alone shall have to pay the penalty of a great sin.' 4 And they all answered him and said: 'Let us all swear an oath, and all bind ourselves by mutual imprecations not to abandon this plan but to do this thing.' 5 Then sware they all together and bound themselves by mutual imprecations upon it.

Date: 200-50 B.C.E.
* Dates are based on scholarly estimates

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.

Date: 200 C.E.
* Dates are based on scholarly estimates