(Ok, for the answer to the last question, read and learn about the science of hadith. In a sentence: Scholars have devised an extremely rigorous process to determine which hadith are authentic, and which are not. You wouldn’t want to spend your whole life following a “hadith,” only to find out it really wasn’t legit, do you?)

A mursal hadith is a hadith where the chain only goes up to a tabi’ee. (So the hadith goes: X narrated, from Y, from Z, … from such-and-such a tabi’een.) Tabi’een are the generation after the companions–they are the sons and daughters and followers of Islam who came after the sahaba. Most hadith continue–the tabi’ee will narrate from a sahaba, who will narrate directly from the Prophet (صلى الله عليه و سلم).

So mursal ahadith are ahadith where the chain cuts off at the tab’iee level; it doesn’t go directly to the Prophet (صلى الله عليه و سلم).

And why is this important? Because a tabi’ee can narrate from another tabi’ee! It doesn’t necessarily mean that they heard it directly from a sahaba, who heard it from the Prophet (صلى الله عليه و سلم).

So the ruling on mursal ahadith? They are considered as da’eef ahadith. All the same rulings apply.

For example, in the issue of “does laughing in salaah break your wudoo?,” imam Abu Hanifa says yes, and cites a mursal hadith as his proof. The majority of scholars disagree, and insha’Allah this is the correct opinion–why?

Because the hadith is mursal (i.e. da’eef), and it contradicts shari’ah principles–why would it break your wudoo inside salaah, but not if you laugh outside salaah? (And these are not the only proofs; only a taste of the discussion.)

Wallahu ‘alam.

Abdul-Bary Yahya. Lecture. AlMaghrib. The Purification Act. University of Toronto, Toronto. November 2006.