Saduqayn
Saduqayn means "the Two Saduqs" and refers to al-Shaykh al-Saduq and his father, Ibn Babiwayh.
- Al-Shaykh al-Saduq whose complete name was Muhammad b. Ali b. Husayn b. Musa b. Babiwayh al-Qummi was among Shi'a scholars of fourth/tenth century and was regarded as the greatest scholar of Qom in hadiths and jurisprudence. Man la yahduruh al-faqih which is one of the Four Books of Shi'a is his most famous work.
- Ibn Babiwayh whose complete name was Ali b. Husayn b. Musa b. Babiwayh was al-Shaykh al-Saduq's father. He was a Shi'a scholar in jurisprudence and hadiths and the religious authority of the people of Qom and its surrounding areas.
In jurisprudential works, when the two have expressed similar opinions, they are addressed as "Saduqayn". Also, in cases when this word is in raf' state in Arabic, for example when it is positioned as Mubtada or the subject of the sentence, it will be changed as "Saduqan".