Surah 3:184, "Then if they reject you (O Mohammed), so were Messengers rejected before you, who came with clear evidence and the Scripture and the Book of Enlightenment."
"And if they accuse thee of lying, even so were accused of lying Messengers before thee who came with clear Signs and Books of wisdom and the illuminating Book." (Sher Ali Edition). Here the Book of Enlightenment and Scripture came down to the Jews as clear evidence of God from the Prophets or Messengers. The Book of Enlightenment is also translated as The Book of Light in Surah 22:8.
Surah 22:8, "And among men is he who disputes about God, without knowledge or guidance, or a Book giving Light (from God)."
The Book of Light in Judaism is known as the The Sefer Zohar, a kabbalistic text written between (539 BCE – 70 CE),but a copy discovered in the 13th century. See Wikipedia article on Zohar.
The Zohar could well be the Book of Enlightenment mention in the Quran since both books deal with esoteric subjects which mystics would be familiar. But we will never be certain. However it does reveal God has authored other works besides the existing scriptures. This is very intriguing to those who seek to uncover the hidden depths of the Quran.
The Quran also mentions other books:
Scrolls of Abraham: The Scrolls of Abraham are believed to have been one of the earliest bodies of scripture, which were vouchsafed to Abraham, and later used by Ishmael and Isaac. Although usually referred to as 'scrolls', many translators have translated the Arabic Suhuf as 'Books'. The Scrolls of Abraham are now considered lost rather than corrupted, although some scholars have identified them with the Testament of Abraham, an apocalyptic piece of literature available in Arabic at the time of Muhammad.
Scrolls of Moses: These scrolls, containing the revelations of Moses, which were perhaps written down later by Moses, Aaron and Joshua, are understood by Muslims to refer not to the Torah but to revelations aside from the Torah. Some scholars have stated that they could possibly refer to the Book of the Wars of the Lord, a lost text spoken of in the Hebrew Bible.
Source: Wikipedia article: Prophets in Islam