Al Mursal is the Hadith which a narrator transmits from another narrator who had not seen or met. It has types and terms according to the scholars of Hadith.
Of which is the absolute Mursal which is: A Follower would say: "The Messenger of Allah (peace be upon him) said" so, the Hadith shall not be an absolute Mursal but after a Follower ascribes it directly to the Messenger of Allah (peace be upon him).
Of which is Al Munqati which is different from the first.
Al Hakim said: And rarely you could find someone who differentiated between them. Al Munqati is of two types:
1- The Isnad would contain a narrator who had not heard the narrator from whom he narrated the Hadith before the chain of transmission reaches the Follower who ascribed the Hadith to the Messenger of Allah.
2- One of the narrators would narrate from a narrator whose name is unknown, so he does not mention the narrator. If a narrator does not mention the name of the narrator from whom he took the Hadith while he knows him, it will not be Munqati because the name of the narrator is known.
Another type is Al Mu dal which is the Hadith in which more than a narrator were omitted from the chain of transmission up to the Messenger of Allah (peace be upon him). For example, Amr ibn Shu ayb narrated that the Messenger of Allah (peace be upon him) did so and so or said so and so then he did not ascribe it to the Messenger or even mention the narrator from whom he took the narration. The least narrators who should be found between the Messenger of Allah (peace be upon him) and Amr ibn Shu ayb are two narrators. So, if the Hadith was ascribed to the Messenger of Allah (peace be upon him) or he mentioned the chain of narration except one narrator, it will not be a Mu dal.
One of the types of Al Mu dal is the Hadith which a follower of the Followers narrated without ascribing it to anyone, so his speech is Mawquf. So, he narrated the Hadith as Mu dal then the Hadith was found connected without omission in another chain of transmission.
Mursal Hadiths were frequently found in the narrators of Medina from Sa id ibn Al Musayyab and from the narrators of Makkah from Ata' ibn Abu Rabah, in the narrators of Egypt from Sa id ibn Abu Hilal, in the narrators of the Levant from Makhul, in the narrators of Basra from Al Hasan Al Basry, and in the narrators of Kufa from Ibrahim ibn Zayd An-Nakh y.
And the most authentic are the Mursal Hadiths of Ibn Al Musayyab because he lived with a group of grand Companions and lived in the time of the Followers and took narrations from them; moreover scholars checked his Mursal Hadiths and found them all with authentic chain of transmission.
People differ regarding accepting the Mursal Hadith.
The view of Abu Hanifah, Malik ibn Anas, Ibrahim An-Nakh y, Hammad ibn Abu Sulayman, Abu Yusuf, Muhammad ibn Al Hasan and those who came after them from the scholars of Kufa is that Mursal Hadiths are accepted and can be used as proofs to the extent that some of them said: They are more correct than Hadiths with connected chain of transmission because when a Follower narrates something, he ascribes the entire narration to the narrator from whom he took the narration. And when he says: The Messenger of Allah (peace be upon him) said, he does not say it but after exerting efforts in knowing the authenticity of the Hadith.
As for the scholars of Hadith or some of them, Mursal Hadiths are not authentic and cannot be set as proofs; this is the view of Ash-Shafi y, Ahmad ibn Hanbal, Ibn Al Musayyab, Az-Zuhry, Al Awza y, and those who came after him from the jurists of Al Hijaz.
Some of the scholars who refused to accept the Mursal accepted the Mursal Hadiths of the Companions because a Companion reports from another Companion and they are all trustworthy.
Some of them conditioned the presence of grand Followers such as Ibn Al Musayyab. It was also said that it is the view of Ash-Shafi y who accepted the Mursal Hadiths of Ibn Al Musayyab and said that all his narrations are ascribed to their original narrators and up to the Messenger of Allah.
The general rule is: If a Follower or a Companion was known with his trustworthiness and reported only from the Companions, his Mursal Hadiths are accepted, but if we do not know that, his Mursal shall not be accepted because they may narrate from other people who did not accompany the Prophet (peace be upon him) during his lifetime.