Abu Jaʿfar Muḥammad ibn ʿAli ibn Al-Ḥusayn ibn Mūsā al-Qummī (ابوجعفر محمد بن علي بن الحسين بن موسی القمي) (after 305/917 — 381/991), commonly known as al-Shaykh al-Saduq (الشيخ الصدوق), or Ibn Babawayh (ابن بابويه), was one of the greatest Shiʿa traditionists and the compiler of Man la yahduruh al-faqih, one of the Four Books of the Shi'a.
Al-Shaykh al-Saduq was the most prominent traditionist and scholar of the hadith school of Qom. Al-Saduq began teaching and narrating hadith from a young age, and continued to do so during his travels. He had many students, and many scholars narrate hadith on his authority. His epithet, al-Saduq (the Truthful), indicates his reliability as a transmitter of hadith in the eyes of Shiʿa scholars.