This epistle is undoubtedly one of the most important writings of Sheikh Al-Islam . Indeed, despite its modest volume, concentrates abundant knowledge characterizing the extent of the knowledge of this scholar, may Allah have mercy on him. It could be that a student (in theology) does not find in encyclopaedias of jurisprudence what this (small) manuscript contains as information. 

The theme of this epistle is (the type of) garment which it is incumbent upon every man and every woman to put on during the performance of prayer. The author has demonstrated, with supporting evidence, that the garment in question is not simply that which a man usually wears to cover his nudity ('Awra) outside his prayers. Much more, he indicated that it is a question of something else; it is a habit that would also cover the shoulders and this, out of respect for the prayer and out of respect for its sacredness and not because the shoulders are part of the private parts ('Awra) to be preserved from the gaze of others.