“Enoch, the seventh from Adam, prophesied”
Enoch, the seventh from Adam, also prophesied about them: 'Behold, the Lord is coming with myriads of His holy ones' (Jude 1:14 BSB)
What it sounds like today
A quotation from a lost saying of Enoch in the Bible.
The cultural key
Readers hunt through Genesis for these words of Enoch and never find them, because Jude is quoting a different book. The lines come from 1 Enoch (1:9), a widely-read Jewish apocalyptic writing from the centuries before Christ that expanded on the brief Genesis note that Enoch 'walked with God' (Genesis 5:24). Jude's audience knew and valued this book, so he cites it the way a preacher today might quote a famous hymn or a respected author, as a fitting and forceful expression of a truth, that the Lord will come with His holy ones to judge the ungodly. Even the designation 'the seventh from Adam' reflects the way 1 Enoch numbered the generations. Jude's use of the book does not necessarily make it Scripture; he employs it as apt and true, much as Paul quotes pagan poets. The larger point is that judgment on the ungodly was foretold from the most ancient of prophets. Knowing the source resolves the puzzle of a Bible verse quoting a book not in the Bible.
Recovered meaning
Jude quotes not Genesis but the book of 1 Enoch, a Jewish apocalyptic work his readers esteemed, to warn of coming judgment. He uses the familiar text as apt and true (as Paul quotes pagan poets), and even 'seventh from Adam' reflects its phrasing.