Do you know for certain the the Quaran is the inspired and authoritative Word of God?
If you are a devoted Muslim, you most assuredly believe that Islam is the only true religion in the world and that the Quran is the written, true Word of Allah (God), which has been given to Muslims by Allah himself, through the prophet Muhammad. I am sure that you, as a true believer in Islam are fully trusting and believing in every word that is written in the Quran.
If this is so, then according to a third chapter of the Quran, you must believe that the Bible (the Scriptures) is also the inspired Word of God.
This is what the Quran say: “It is He Who has sent down the Book (the Quran) to you (Muhammad) with truth, confirming what came before it. And he sent down the Taurat (Torah, which is of the Old Testament of the Bible) and the Injeel (Gospel, which is the New Testament of the Bible)”. (Surah 3:3)