Allah (swt) has declared in the Qur’ān: ﴾O you who believe, obey Allah and obey the Messenger…﴿ (4:59). Accordingly, Islamic religious life is based on the instructions of the Qur’ān and the authentic Sunna. This treatise brings together around 90 verses of the Qur’ān and 340 hadiths—under the headings of 25 ‘principles’—which focus on the very essentials of Islam, including: the meaning of Islam and faith; exhortations of a spiritual nature, such as trusting in the Divine, remembrance of Him, loving Allah and His Messenger, abstaining from sin, gratitude and patience; and commandments of a legal nature, relating to prayer, recitation of the Qur’ān, fasting, hajj, zakat, marriage, childrearing and good social conduct.