And Enoch also, the seventh from Adam, prophesied of these, saying, Behold, the Lord cometh with ten thousands of his saints, To execute judgment upon all, and to convince all that are ungodly among them of all their ungodly deeds which they have ungodly committed, and of all their hard speeches which ungodly sinners have spoken against him.
-Jude 14-15
Answer: The famous verse quoted by Jude was originally taken from the Book of Enoch. It is a widely accepted book before and during the early days of Christianity, but was never been canonized in the Old Testament.
The Book of Enoch is a collection of apocalyptic writings attributed to the man who was only known from few lines in the Bible. According to the book, Enoch was a righteous man who was the seventh on the generations of Adam. God was pleased on him for his righteousness , thus he was caught up in heaven by the Spirit. During his journey, he went through different heavenly realms and have seen the hierarchal ranks of the angels. The last of these heavenly realms is where God's throne is. On these events, Enoch was shown revelations that were never known by mankind during those ancient days. He was taught to number the stars and outlined the constellations. He also learned about the seasons on earth and even divided the days to 365 for each year. Aside from this, he also witnessed the prophetic events that happened in the days of Noah. These includes how a horde of angels lusted over the daughters of men (Genesis 6:2), how there were giants on those days (Genesis 6:4), the plight of the fallen angels and how they were bound in chains under darkness (2 Peter 2:4; Jude 6). Lastly, it was revealed unto him the great flood that engulfed the earth, the rise of the chosen people of God (Israelites), the days of Jesus Christ and the reign of God's kingdom on the last days. Eventually, Enoch returned to earth and shared to his family what was revealed to him by God. He then blessed them and bid farewell, for God ordained him to return in heaven. Thus the famous verse, "Enoch walked with God, and he was not, because God took him (Genesis 2:24)." His son Methuselah (Genesis 5:22-27), wrote the words of his father that he revealed to them and was the Book of Enoch that existed today.
The Book of Enoch
Although one of the highly esteemed book of the early Christians, the Book of Enoch only had its place on the Pseudepigrapha or Apocrypha of the Orthodox church. Its earliest copies were dated to have been existed in 2nd and 1st century B.C. It was called the Ethiopic Enoch, because it was preserved on its entirety into an old Semitic language formerly spoken in Ethiopia. Little was known of this book until three complete Ethiopic manuscripts were discovered in northeastern Africa in the late 18th century. However, after the discovery of the Dead Sea Scrolls on the cave of Qumran in mid 20th century, scholars believed that the original texts were actually written in Hebrew and Aramaic.