The Qur’an mentions at least three main Islamic scriptures which came before the Qur’an by name.
According to the Qur’an, the Tawrat was revealed to Moses, but Muslims believe that the current Torah, although it retains the main message, has suffered corruption over the years, and is no longer reliable. Moses and his brother Aaron used the Torah to preach the message to the Banu-Isra’il (Children of Israel). The Qur’an implies that the Torah is the longest-used scripture, with the Jewish people still using the Torah today, and that all the Hebrew prophets would warn the people of any corruptions that were in the scripture.
The Qur’an mentions the Zabur, often interpreted as being the Book of Psalms, as being the holy scripture revealed to King David. Scholars have often understood the Psalms to have been holy songs of praise. The current Psalms are still praised by many Muslim scholars, but Muslims generally assume that some of the current Psalms were written later and are not divinely revealed.
The Injil was the holy book revealed to Isa, according to the Qur’an. Although many lay Muslims believe the Injil refers to the entire New Testament, scholars have pointed out that it refers not to the New Testament but to an original Gospel, written by God (Allah: see God in Islam), which was given to Isa. Therefore, according to Muslim belief, the Gospel was the message that Isa, being divinely inspired, preached to the Children of Israel. The current canonical Gospels, in the belief of Muslim scholars, are not divinely revealed but rather are documents of the life of Isa, as written by various contemporaries, disciples and companions. These Gospels, in Muslim belief, contain portions of Isa’s teachings but don’t represent nor contain the original Gospel, which has been corrupted and/or lost, which was a single book written not by a human but by God.