To write this book, I based myself on the commentaries on the “Forty hadiths” written by An-Nawâwî, Ibn Daqîq Al- 'Îd, Ibn Rajab, and Ibn 'Uthaymîn, as well as Fath Al-Bârî by Ibn Hajar Al- Asqalani. I advise students to memorize these hadiths which mark the gift of conciseness of the noble Messenger.