A book translated into Japanese contains the forty Prophetic hadiths that Imam Nawawi chose to be included in this book. Each hadith contains a great Islamic rule. All seekers of hereafter reward have to know and study these hadith, for they include important Islamic bases.

This article is quoted and translated from the book of ’’Summary Of Islamic Jurisprudence ’’ about the virtue of Knowledge,learning it ,teaching it and the punishment of concealing it.