One must believe in the Holy Books that were revealed to the Messengers of Allah the prophets in Islam, which are numerous.  The most well-known holy books are the Qur’an, the Torah, the Injil (bible), and az-Zabur. The number of the true Holy Books is 104, as Shaykh Shams ad-Din ar-Ramliyy reported in his book ‘Nihayat al-Muhtaj fi Sharh al-Minhaj’.