"O you who believe, believe in Allah and His Messenger, and the Book which He sent down upon His Messenger, and the Book which He sent down earlier. And whoever disbelieves in Allah, and His Angels, and His Books, and His Messengers, and the Last Day, then he has certainly gone far astray." (the Quran 4:136)
“The Book which He sent down earlier” or “the Scripture which He sent down before” is in singular form, which means that there is “only” one Book that every believer has to believe in other than the Quran. But which one? There are many books that had been sent down before Muhammad. The Torah, Psalms, and the Gospel, to name a few; not to mention the books that were given to the Prophets like Isaiah, Jeremiah, Ezekiel, Jonah, etc.
To identify which book that the Quran talked about in the verse above, we have to look in some other verses:
1. “And before it (the Quran) was the Scripture of Moses to lead and as a mercy. And this is a confirming Book in an Arabic tongue to warn those who have wronged and as good tidings to the doers of good.” (the Quran 46:12)
2. They said, "O our people, indeed we have heard a Book revealed after Moses (that is the Quran) confirming what was before it which guides to the truth and to a straight path. (the Quran 46:30)
3. Is he then who has with him clear proof from his Lord, and a witness from Him recites it and before it (the Quran) is the Book of Moses, a guide and a mercy? (the Quran 11:17)
4. But when the truth came to them from Us, they said, "Why was he not given like that which was given to Moses?" Did they not disbelieve in that which was given to Moses before? They said, "[They are but] two works of magic supporting each other, and indeed we are, in both, disbelievers." Say, "Then bring a scripture from Allah which is more guiding than either of them (the Quran and the Book of Moses) that I may follow it, if you should be truthful." (the Quran 28:48-49)
5. And indeed, We already brought Moses the Book; so do not go into wrangling about receiving it; and We made it for a guidance to the sons of Israel (the Quran 32:23)
From the verses above we can conclude that the Book or the Scripture before the Quran is the Book of Moses. Now the question is, what is the Book of Moses? Is it the Torah, or is is something else other than the Torah?
Many believe that the Torah is the Book that was given to Moses, and the Book that was given to Moses is called the Torah. This is a false assumption. Never in the Quran that the Book given to Moses is called the Torah, and the Quran never states that the Torah is given to Moses. The Quran simply says that the Torah is sent down to the sons of Israel, but not to Moses the prophet. So, we must distinguish between the Torah and the Book of Moses.
The Torah is the first five books in the Bible, that is Genesis, Exodus, Leviticus, Numbers, and Deuteronomy. According to the Documentary Hypothesis, the Torah is not written by Moses himself, but by several authors whom they call as J, E, D, and P. That can explain why there are some contradictions and the doublets in the Bible, particularly in the Torah, such as how many pair(s) of animals that were in the ark of Noah: one pair or seven pairs, who sold Joseph: the brothers, the Midianites, or the Ishmaelites, why did they told the story of the quails twice, and so on.
Since there are contradictions and doublets in the Torah, we can conclude that the Torah is not written by Moses. So we can say that the Book of Moses that the Quran talked about is not the Torah.
So, what is actually the Book of Moses?
I believe that what is written in the Book of Moses is almost identical to what is written on the Tablets (Arabic: alwah). In surah Al A’raf, it is stated that God gave the Tablets to Moses, where instruction and explanation for all things were written on it (the Quran 7:145). It is worth noting that in the surah Al An’am 154, the verse uses the exact phrase watafseelanlikulli shay-in (The Quran 6:154). Therefore, it is very likely that the what was written in the Book of Moses as described in the Quran 154 is the same as what was written in the Tablets mentioned in the Quran 7:145 and 7:154.
What was written in the Book of Moses?
Previously, I mentioned that according to the Documentary Hypothesis, the Torah is written by at least four different authors whom they call as J, E, D, and P. Well, actually not all of parts of the Torah is written by those four. At least three parts of the Torah is not written by them. Those parts are the Ten Commandments in Exodus 20, the Covenant Code in Exodus 21-23, and the Holiness Code in Leviticus.
In The Bible with Sources Revealed, on commentary on the Ten Commandments in Exodus, Richard Elliott Friedman wrote, “The text of the Ten Commandments here does not appear to belong to any of the major sources (that is it’s not from J, E, P, or D). It is likely to be an independent document, which was inserted here by the Redactor". Furthermore, Mr. Friedman added, “Exod 21:1-23:19 is a law code known as the Covenant Code. It was originally a separate, independent document, but it was used by the author of E as part of the work of E."
It is likely that both the Ten Commandments and the Covenant Code are two parts that were originally from much older text than any of J, E, P, and D documents. It is possible that those two parts were copied from the Book of Moses.
I believe that both the Ten Commandments and the Covenant Code in Exodus are part of the Book of Moses. I also believe that those two parts are preserved from fraud, editing, changing, etc. Maybe the other parts of the Bible are not free from errors, fraud, contradictions etc, but not those two parts. That’s why the Quran still confirms the previous book (i.e. the Book of Moses), and that’s why the believers are commanded to believe in the previous Scripture (the Book of Moses).