Why there are specifically five daily prayers, the reasoning behind the number of rak'ahs in various prayers (e.g., why Dhuhr has four), and the significance of prayer timings.
You can find the complete digitized version of Israr-ul-Ahkam Bah Anwar-ul-Quran available for free download in multiple formats. asrar ul ahkam pdf
The spiritual and physical benefits of fasting during Ramadan. Why there are specifically five daily prayers, the
The social and spiritual wisdom behind the compulsory alms-giving. why Dhuhr has four)
The essence and logic behind the declaration of faith.