Intellect demands that a leader must be superior to his followers. If the followers are better than the leader in any of the aspects in which they are supposed to follow him, then the leader would actually become a follower in that aspect. Hence, the position of divine leadership is such that a divine leader must excel and be superior to all others in every aspect, be it matters of the world or hereafter. A divine leader, Imam and Caliph must, not just be second to none but there should not be even the remotest of similarities between him and the others. Only the one who possesses such excellences deserves to be accepted as a divine leader and Imam.
However, the most important and critical virtue which a divine leader, Caliph and an Imam should possess is knowledge. After the martyrdom of Holy Prophet (peace be upon him and his progeny), it is foolish to accept and follow anyone apart from Ali Ibn Talib (peace be upon both of them) as a divine leader, Caliph and Imam because there was absolutely none among the companions (Ashaab) who were even remotely close to him in knowledge.
This superiority is proven from the claim and challenge by Imam Ali Ibn Talib (peace be upon both of them) himself when he openly announced:
سَلُوْنِی قَبْلَ اَنْ تَفْقِدُوْنِی
“Ask me before you lose me”
Any person will throw open such a challenge only if he is certain about the fact that there is no one more knowledgeable than him. This challenge was not restricted to any religion, custom, person, section of society, worldly matter or that of the hereafter, etc. It was an open challenge to anyone and everyone. Also, neither did anyone else in the history of mankind utter these words before or after him nor did anyone from among the companions or Taabe’een falsify this claim by asking anything to him which he could not reply. Every seeker of knowledge was satiated when he came to the doorstep of Imam Ali Ibn Abi Talib (peace be upon both of them). This superiority is unanimously accepted by all scholars of both sects.
Ahle Tasannun scholars consider Saeed Ibn Musayyab as Syed al-Taabe’een (chief of all Taabe’een) and the greatest scholar in Madinah, rather the most knowledgeable person of his time in matters related to Halaal (permissible) and Haraam (prohibited) such that even if he quoted a tradition without the chain of narrators, they would still accept those traditions as reliable. Saeed Ibn Musayyab says regarding the superiority of Ameerul Momineen Ali Ibn Abi Talib (peace be upon both of them) in knowledge over all other companions:
لَمْ یَکُنْ اَحَدٌ مِنَ الصَّحَابَۃِ یَقُوْلُ سَلْئُوْنِی اِلَّا عَلِیُّ بْنُ اَبِی طَالِبٍؑ
“There was absolutely none among the companions who claimed “Ask me”, except Ali Ibn Abi Talib (peace be upon both of them).
Even after this, if someone choses to follow anyone else apart from Ali Ibn Abi Talib (peace be upon both of them) as the successor of Holy Prophet (peace be upon him and his progeny), then it is as if he has chosen ignorance over knowledge.
Ahle Tasannun References:
- Fazaael al-Sahaaba by Ahmad Ibn Hanbal, vol. 1, p. 646, H. 1098
- Riyaaz al-Nazarah by Al-Muhibb al-Tabari, vol. 3, p. 212 wherein he considers this tradition by Saeed Ibn Musayyab to be correct (Saheeh)
- Seyaro A’laam al-Nobalaa by Zahabi, vol. 4, p. 218
- Al-Ghadeer by Allamah Amini (may Allah have mercy on him), vol. 6, p. 272
 Taabe’een were those who did not see the Holy Prophet (peace be upon him and his progeny) but instead they had witnessed and interacted with his companions