This study includes an application for the theory of hadith transmission system based on probability calculation by the transmitters. The transmitter who is selected in order to remove the unknown character is Mūsā b. Anas b. Mālik of the Tābi‘īn (the ones who listened to hadiths from the people who saw the Prophet.) The reliability coefficient based on unknown transmitters (η) is calculated by determining and analyzing all the transmissions of the transmitter with chain of reporters that are found in the sources. Besides, based on the conclusions, the power (P) of transmitter is brought to light as well and all of them are displayed in a table. In the conclusion of the study an appraisal is made by comparing the degrees of the words rebuttal (jarḥ) and amendment (ta‘dīl) that were envisaged by the hadith critics regarding the transmitter with η which is calculated by the theory of transmission system of hadith based on probability calculations that is presented here as an example.