The status of ‘Ali ibn Abi Taalib and his sons
27-1-2011 | IslamWeb
Question:
Why don’t we, the Ahlus-Sunnah (people of the Sunnah), acknowledge the caliphate of ‘Ali ibn Abi Taalib and his sons, may Allaah be pleased with them?
Answer:
All perfect praise be to Allaah, the Lord of the worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His Slave and Messenger.
Ahlus-Sunnah unanimously agree that ‘Ali ibn Abi Taalib 
was an Ally of Allaah the Almighty, because he was among the first people to embrace Islam, about whom Allaah the Almighty Says (what means): {And the first forerunners [in the faith] among the Muhaajireen [emigrants] and the Ansaar [helpers] and those who followed them with good conduct - Allaah is pleased with them and they are pleased with Him, and He has prepared for them gardens beneath which rivers flow, wherein they will abide forever. That is the great attainment.} [Quran 9:100].
It is enough that the Prophet, sallallaahu ‘alayhi wa sallam, confirmed this in many Hadeeths. The Prophet, sallallaahu ‘alayhi wa sallam, said that loving `Ali and taking him as an ally is an indication that a person loves the Prophet, sallallaahu ‘alayhi wa sallam, and takes him as an ally, and he, sallallaahu ‘alayhi wa sallam, supplicated to Allaah the Almighty to be an ally to whoever supports ‘Ali and to be an enemy of whoever shows enmity towards him. [Ahmad, At-Tirmithi, Ibn Maajah and Al-Bayhaqi].
As for the claim that he was the worthiest person for the caliphate after the Prophet, sallallaahu ‘alayhi wa sallam, i.e., he was worthier than Abu Bakr and ‘Umar 
this is unacceptable because there is a consensus that Abu Bakr and ‘Umar were better than him (in the sight of the Prophet 
) and that they were worthier of the caliphate than him. He himself acknowledged this and never disputed it, and he gave them his oath of allegiance as Caliphs.
Ahlus-Sunnah, however, differ about preferring ‘Uthmaan to ‘Ali but the majority hold the opinion that ‘Uthmaan holds a higher status than ‘Ali .
Some wrongdoers believe in another kind of leadership, that is, that ‘Ali and his sons are infallible and they have the right to be the religious commanders of the faithful. Of course, this is false as there were many Muslims among the Companions and later generations who were better than some of the descendants of 'Ali . Furthermore, preference in Islam is not based upon lineage and kinship to the Prophet, sallallaahu ‘alayhi wa sallam; rather, it is based upon piety and faith. Allaah the Almighty Says (what means): {Indeed, the most noble of you in the sight of Allaah is the most righteous of you. Indeed, Allaah is Knowing and Acquainted.} [Quran 49:13].
Ahlus-Sunnah Wal-Jamaa‘ah (the mainstream People of the Sunnah) state that no one is infallible except the prophets - they were infallible against mistakes in conveying the revelation and against major sins.
The household of the Prophet, sallallaahu ‘alayhi wa sallam, are included in his saying, sallallaahu ‘alayhi wa sallam, that all humans err and the best among those who err are those who repent. [Ahmad, At-Tirmithi and Ibn Maajah. (Hasan (Sound): Al-Albaani]
Also, they are included in the Divine address to all people in the Qudsi (Sacred) Hadeeth narrated on the authority of Abu Tharr in which the Prophet, sallallaahu ‘alayhi wa sallam, said that Allaah the Almighty calls out to His slaves saying that they all commit sins day and night and He forgives all sins. [Muslim].
Allaah Knows best.