This work by one of 20th century's greatest exponents of Islam explains at length the place of Prayer, Zakah, Fasting and Hajj in the context of the Shariah, their legal position, worth and importance in the religious structure. This work, first published in Arabic in 1968, represents the rich Islamic literature on the subject of worship by scholars of the past. It also discusses how each of these pillars of Islam is represented in other religions. The subjects of the book are the four famous fundamental duties. Salat, Saum, Zakat, and Hajj and along with regulations 'their logical advantages and significance and similarities and differences in respect of the modes of worship in other religious communities have also been discussed. It has, thus. at once become a treatise on jurisprudence, scholastic theology and religious teachings and principles.