Book of Jubilees 49:2
For on this night -the beginning of the festival and the beginning of the joy- ye were eating the passover in Egypt, when all the powers of Mastêmâ had been let loose to slay all the first-born in the land of Egypt, from the first-born of Pharaoh to the first-born of the captive maid-servant in the mill, and to the cattle.
Background and history of Book of Jubilees, and issues with this book.
R. H. Charles, The Book of Jubilees, in The Apocrypha and Pseudepigrapha of the Old Testament, vol. 2 (Oxford: Clarendon Press, 1913). Public domain in the United States (published 1913). Charles died in 1931, so the book is in the public domain in the United Kingdom. The verse text is the Joshua Williams transcription at pseudepigrapha.com. Jubilees 1:8 and 1:9 are divided at the break in the 1902 Clarendon scan (archive.org bookofjubileesor00char), where verse 9 begins “For they will forget.” That scan also numbers the angel-of-the-presence sentence as 1:29. Editorial brackets in the translation are Charles’s.