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.'
Testament of Solomon 21
21 Next, I summoned another demon to appear before me; immediately there approached me a demon bound, and I asked him, 'Who are you?' But he glared at me with fury and retorted, 'And who are you?' And I replied to him, 'Though you are punished, you must still answer me.' He, filled with rage, said to me, 'How should I answer you, since you are a human and I was born from an angel's seed by a daughter of man? Our kind naturally speaks overbearingly to earth-born humans. My star shines brightly in the heavens, and people call it by different names—some call it the Wain (the Big Dipper), others the Dragon's Child. I stay close to this star. So, do not ask me too many questions, for your kingdom too will soon end, and your glory is but for a short while. Soon, your rule over us will end, and then we will have dominion over mankind again, so that they will revere us as gods, not realizing they are only men.'
Notes and References
"... This reconstructed etiology explains how it is that the giants could become so openly identified as demons at a later stage ... see the Testament of Solomon 5:3 and 17:1. In 5:3 (within the section 5:1–11), the author reinterprets the demon Asmodaeus – this is a deliberate reference to the Book of Tobit that follows the longer recension (compare Codex Sinaiticus at 3:7–8, 17; 6:14–15, 17; 8:2–3; 12:15) – one born from a human mother and an angel. In the latter text (in the passage 17:1–5) the demonic power thwarted by Jesus (in an allusion to Mark 5:3) is identified as having been one of the giants who died in the internecine conflicts (compare 1 Enoch 7:5 and 10:12). Similarly, Pseudo-Clementine Homilies 8.12–18 refers to the giants, which are designed as both “bastards” and “demons” in the ante-diluvian phase of their existence. Here they are said to have survived the Flood in the form of disembodied “large souls” whose post-diluvian activities are proscribed through “a certain righteous law” given them through an angel ..."
Stuckenbruck, Loren T. The Myth of Rebellious Angels: Studies in Second Temple Judaism and New Testament Texts (pp. 15-16) Mohr Siebeck, 2014