The determining requirements are Islam, the historical free-person condition, a surplus nisab, and the arrival of Eid dawn. The manual distinguishes personal liability, minor children, adults, spouses and historical enslaved categories.
Wheat requires half a saʿ; dates, raisins and barley require one saʿ each. The weight of the saʿ has differing reported Hanafi interpretations. Advance payment is permissible, payment before the Eid prayer is preferred, and a delayed payment remains due. The next book is Kitab al-Sawm.