Al-Shaʿbī said, “Knowledge is to be taken from six men: ʿUmar, ʿAbd Allāh, and Zayd—their learning resembles one another—and ʿAlī, Ubayy, and Abū Mūsā—whose learning likewise corresponds, each borrowing from the others.” (1)

Dāwūd reported from al-Shaʿbī: “The judges of the Muslim community are ʿUmar, ʿAlī, Zayd, and Abū Mūsā.” (2)

Usāmah ibn Zayd narrated—on the authority of Ṣafwān ibn Sulaym—that “No one issued legal verdicts in the mosque during the time of the Messenger of Allah ﷺ except these four: ʿUmar, ʿAlī, Muʿādh, and Abū Mūsā.” (3)

Abū Burdah related that his father said, “I learned the iʿjām (placing the dots on the letters) only after the death of the Prophet ﷺ, so my handwriting looked like scorpions.” (4)

Ayyūb transmitted from Muḥammad that ʿUmar said, “In Syria there are forty men; any one of them, if he were put in charge of the ummah’s affairs, would be adequate.” He summoned them, and a group came—among them Abū Mūsā. ʿUmar said to him, “I am sending you to a people among whom Satan has pitched his camp in their midst.” Abū Mūsā replied, “Then do not send me.” ʿUmar said, “There is jihad there and frontier garrison duty (ribāṭ).” So he dispatched him to Basra. (5)

Al-Ḥasan al-Baṣrī said, “No rider ever arrived there who was better for its people than Abū Mūsā.”

Ibn Shawdhub said, “When Abū Mūsā had performed the dawn prayer, he would turn toward the rows, taking each man in turn and teaching him to recite. He entered Basra on a dapple-grey camel, and on that same camel he departed when—”