As for the links between some parts of the Qur’ân and books used by Christians and Jews at the time. They have been used by some orientalists such as Blachère and missionaries to try and prove their point that the Qur’ân was just copied from these books.
There is the list of religious books mentioned by Blachère :
-Genesis (Bible, in Hebrew, not translated in Arabic at the time).
-The apocryphal gospel of the childhood of Jesus, Armenian version, not translated in Arabic at the time.
-The Talmud (In Hebrew and Aramaic, not translated in Arabic at the time).
-The Judaic Midrash (not translated in Arabic at the time).
-The Targum (Paraphrase of the Old Testament in Chaldean, not translated in Arabic at the time)
-The New Testament (Bible, in Greek or Latin, not translated in Arabic at the time).
-Pseudo Matthew (I actually do not know what language this one was written in, but Arabic is not an option).
-The Wisdom of Ahiqar (Arabic and Ethiopian version).
-Anecdota syriaca (In Assyrian/Aramaic ?)
-Some even claim the holy Qur’ân was partly copied from the Avesta, whose language is Avestic or Zend !
These accusation are mutually defeating for how would MuHammad (çalla-llâhu ^alayhi wasallam) have had such encyclopaedic references available to him? Many of these books were extremely rare and are hard to find to this day. They were often written in languages known only by a minority of experts.
These slanderer suggest that MuHammad (çalla-llâhu ^alayhi wasallam) mastered these languages while managing to hide this exceptional knowledge from his environment, in the little town Mecca was at the time, where everybody knew everybody else.
Or do they suggest that the Prophet (çalla-llâhu ^alayhi wasallam) had such a rich library, which left no trace, was never discovered, neither by friends nor foes?
Some Pagans claimed he had slaves dictating to him, but where would he have managed to gather such scholarly slaves? In Mecca? It would have been hard to gather them in one place in the Persian and Byzantian capitals.
The links between some Qur’ânic verses and other religious books (some of which I know myself) are due to the traces left in those forged books, of the previous revelations. They show that the last revelation confirmed the previous ones, while denouncing what had been tampered with.