NAFSI and MUQADDAMI

In this classification, NAFSI Wajib acts are those which are obligatory by themselves, and are not a prelude to another obligation. For example, it is Wajib to rescue a person who is on the verge of being burnt, drowned or harmed to death.

Muqaddami obligation, besides being Wajib itself, is actually a mean to performing another Wajib act. For example, it is Wajib to rescue a person who has fallen into a well, but preparing for the rescue by way of procuring a rope or any other implement is a Muqaddami Wajib. Similarly, Haj is a NAFSI Wajib, but attending to its prerequisites like getting a passport, buying the tickets, and other necessary preparations will be termed Muqaddami. In the case of the daily prayers, for example, Wudhu and Ghusl at the time of the prayers would be called Muqaddami.

Adapted from the book: "Fiqh and Fuqaha"