Translated to English, Kitab al-I'tisam by Abu Ishaq Ibrahim Ibn Musa al-Shatibi (d.790 AH.), translated by Mohammed Mahdi al-Sharif. Two volumes in one book.

Al-i'tisam is one of the earliest - if not the first - works to be compiled about Bid'a. Imam al-Shatibi's strict analysis and complete adherence to the verification of all sciences makes him one of the unique individuals capable of determining what is Bid'a in the Islamic science. Although there is a similar work written by Imam Ibn Abi Shama, the teacher of Imam Nawawi, this work by al-Shatibi stands out as the most referenced book. The Imam adheres to his Maliki school of Law, famous for being strict in what is Bid'a (non-Islamic ideas and practices) and what is Mashru' (legal, legitimate).