In Islam, a list of authorities who have transmitted accounts of the teachings or actions of Muhammad , one of the Companions of the Prophet , or of a later authority.
Each of these accounts, known as Had 012B; th , includes an isn 0101; d that gives the chain of authorities by which it has been handed down, using the form, "It has been related to me by A on the authority of B on the authority of C on the authority of D that Muhammad said...." See also ilm al-had 012B; th .