If his statement(1), “The most knowledgeable member of my community concerning what is lawful and unlawful is Muādh ibn Jabal,” has a sounder chain of transmission and is clearer(2) in its import, then it is evident that anyone who adduces this to argue that Ali was more knowledgeable(3) than Muādh is ignorant. How much more so anyone who makes the same claim concerning Abu Bakr and Umar, both of whom were more knowledgeable(4) than Muādh?! This is so even though some scholars grade the hadith mentioning Muādh and Zayd as weak, while others grade it acceptable; as for the hadith mentioning Ali, it is weak or baseless.
The hadith, “I am the city of knowledge, and Ali is its gate,” is even weaker and more tenuous. It is therefore counted only among(5) fabricated reports, even though al-Tirmidhī narrated it. Ibn al-Jawzī also cited it and explained that all its chains of transmission are fabricated. Indeed, its falsity is evident from the text itself(6): if the Prophet, peace and blessings be upon him, were the city of knowledge, if that city had only one gate, and if only one person conveyed knowledge from him, then the whole affair of Islam would be undermined. For this reason, Muslims agree that knowledge from him cannot be conveyed by only one person(7). Rather, those who convey it must be sufficiently numerous to establish mass transmission, such that their report yields certain knowledge for anyone who was not present.