What is the ruling on using a mursal hadith as evidence?

The Shaykh : It deserves to be the primary opinion.

The questioner : The last one?

The Shaykh : Yes; because the correct view is that a mursal hadith is like any weak hadith whose weakness is not severe. It is clear that a mursal hadith is weak, so it is not used as evidence, as some say. Rather, it is not used as evidence, as others say. However, not using it as evidence is the same as not using any other weak hadith as evidence, even if it is connected, but has a defect that makes its chain weak. Therefore, a mursal hadith is like any weak hadith that is not used as evidence unless it is supported by certain circumstances. Among these is what you mentioned earlier, which is what Imam al-Shafi'i stated previously: that it comes through another connected path. It is not required that this other connected hadith, or this other connected chain, be authentic, nor even good in itself. It is sufficient for it to be weak in a way that it can be cited as corroboration. In that case, the mursal hadith is used as evidence like any other weak hadith that has a corroborating narration whose weakness is not severe. This is the stronger opinion among the views stated regarding the mursal hadith: it is used as evidence and it is not used as evidence. The correct view is: it is not used as evidence absolutely, except if it comes through another connected path.
As for if it comes through another mursal path with a correct chain, a mursal hadith does not serve as a corroborator for a mursal hadith like it. The reason for this is subtle: it is possible that the pivot of the two mursal hadiths—or, if you wish, the two mursal narrators—rests on a single shaykh who is the missing, unknown link, since neither the first nor the second mentioned who narrated this hadith to them. Therefore, Imam al-Shafi'i stipulated the aforementioned condition that it come through another connected path; meaning, the narrator of the hadith appears in it to be a Companion. The reason—and there is no secret in knowledge, so it is a reason, not a secret—for not using the mursal hadith as evidence is the lack of knowledge of the thing the mursal narrator did not mention. It is possible that it is a Companion, in which case it would be authentic. But it is possible that it is not a Companion; that it is a Tabi'i, in which case it is possible that he is trustworthy, as it is possible that he is not trustworthy. Due to these possibilities that arise regarding the mursal hadith, it is said: the mursal hadith is not used as evidence. This is the opinion of the majority of hadith scholars. As for the jurists, their disagreement on this is well known, and their strongest opinion is the opinion of Imam al-Shafi'i that we mentioned earlier. This is the stronger opinion regarding the mursal hadith.