Sahl ibn Ziyad Razi is a well-known narrator who has been mentioned in the chains of narration of many Hadiths and documents. The majority of early Shiite Rejali sources prior to Imamia have undermined him, while some latter Rejali and Fiqhi sources have defended the trustworthiness of this prolific narrator and described his narrations as authentic and consistent. Ayatollah Khamenei is one of the few scholars who have neither defended the absolute trustworthiness of Sahl ibn Ziyad nor ruled out that all of his Hadiths are invalid. Rather, he has strengthened the theory of the reliability of Sahl's Hadiths in the noble book of al-Kafi. He believes that the numerous statements of the predecessors in weakening Sahl ibn Ziyad make it difficult to defend his absolute trustworthiness, but on the other hand, the high status of Sheikh Koleini in hadith studies and his great interest in transmitting Sahl's Hadiths in a book like al-Kafi, brings about trust in the hadiths of this narrator regarding al-Kafi. This theory has tangible implications in the areas of ijtihad and Fiqh for Ayatollah Khamenei.