there was the book of moses before this a guide and a mercy and here is this book confirming it in lucid language warning those who are wicked and giving happy tidings to the righteous.
ومن قبله كتاب موسى إماما ورحمة وهذا كتاب مصدق لسانا عربيا لينذر الذين ظلموا وبشرى للمحسنين