Literally means "succession, consecutive." Islamically refers to hadith which is narrated by such a large number of people that it is impossible (Allahu Alim (God is all-knowing)) that they have invented a lie.Its conditions include:
(1) That it be narrated by a large number of people. Scholars differ about the actual number required (2) That this number is found in every level of the isnaad (3) That it is impossible that they could have gathered together upon a lie.