Book of Enoch (1 Enoch) 72:26
And on that day the night becomes longer and amounts to the double of the day: and the night amounts exactly to twelve parts and the day to six.
Background and history of Book of Enoch (1 Enoch), and issues with this book.
R. H. Charles, The Book of Enoch (London: SPCK, 1917), public domain. The verse text is the English Wikisource transcription of that translation. Charles’s editorial signs are kept. He rearranges some verses in chapters 5, 39, 90, 91, and 106, so those chapters are not a straight 1, 2, 3 sequence.