The jurists of Medina also learned the religion during Umar’s caliphate. Muādh taught the people of Yemen more extensively and remained among them longer than Alī did. Hence, the people of Yemen transmitted more from Muādh ibn Jabal than they did from Alī. Shurayh and other leading Successors studied jurisprudence under Muādh ibn Jabal. When Alī arrived in Kufa, Shurayh was already serving there as a judge; both he and Ubayda al-Salmānī had studied jurisprudence under others. Thus, Islamic knowledge had spread throughout the cities before Alī came to Kufa.

Ibn Hazm(1) said: “Some Rāfidīs have argued that Alī was the most knowledgeable of them all.” He then said: “This is a lie. A Companion’s knowledge can be ascertained in only one of two ways, with no third: first, the abundance of his narrations and legal opinions; and second, the frequency with which the Prophet—may Allah bless him and grant him peace—entrusted him with public duties. It is inconceivable and false that the Prophet—may Allah bless him and grant him peace—would appoint someone lacking knowledge. Such appointment is the strongest testimony to his knowledge and its breadth.

“Upon examining this, we found that the Prophet—may Allah bless him and grant him peace—appointed Abū Bakr to lead the prayer in his presence throughout his illness, while all the leading Companions were present, including Umar, Alī(2), Ibn Masūd, Ubayy, and others(3). This was unlike his appointment of Alī as his deputy when he went out on a military expedition, for that authority extended only over the women(4) and those with legitimate excuses. It therefore necessarily follows that Abū Bakr was the most knowledgeable of all people regarding prayer and its ordinances, and the most knowledgeable among those named regarding it; prayer is the pillar of Islam(5). We also found that he appointed him to oversee alms, so it necessarily follows