Book of Jubilees 50:4
Wherefore I have ordained for thee the year-weeks and the years and the jubilees: there are forty-nine jubilees from the days of Adam until this day, [2410 A.M.] and one week and two years: and there are yet forty years to come (lit. 'distant') for learning the [2450 A.M.] commandments of the Lord, until they pass over into the land of Canaan, crossing the Jordan to the west.
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.