The word tabarra is derived from the verb bara'a meaning to be free of someone. Thus, tabarra minhu means he declared himself not to be connected to or implicated with him. According to Lisan al-Arab, the word tabarra means having nothing to do with or disassociate from some one or something. The Koran says, "And those who followed would say: If only we had one more chance, we would clear ourselves of them, as they have cleared themselves of us" (2:167). In sum, tabarra means to keep away from the wicked and the enemies or disassociation from them.
Muawiya was the first to introduce the tradition of tabarra in Syria, reviling Ahl al-Bayt. Ibn Abi al-Haddid writes in Sharh Nahj al-Balagha (4:63) that, "Muawiya appointed a group of the Companions of the Prophet to fabricate traditions concerning Ali to slander and renounce him. Among them were Abu Huraira, Amr bin A'as and Mughira bin Shuba."
When a peace treaty concluded between Hasan and Muawiya, it was resolved not to revile Ahl al-Bayt. The third term out of five terms in the treaty reads: "He (Muawiya) should abandon cursing the Commander of the faithful and the practice of using the personal prayer in the ritual former prayer against him, and that he should not mention Ali except in a good manner." Abul Faraj Ispahani writes in Maqatil al-Talibiyyin (p. 26) that, "Hasan also asked Muawiya on that occasion not to curse Ali. He disagreed with him on refraining from cursing, and agreed with him that Ali should not be cursed while he hear that." Then Muawiya broke that term and planted the seed and his descendants watered it, making it the tree of the boxthorn in the history of Islam. This practice continued many years. The Umayyad caliph Umar bin Abdul Aziz at last abolished it, and ordered his governors all over the Islamic countries to prevent people from cursing Ahl al-Bayt.
Most of the early Shi'ites could not tolerate the tabarra against Ahl al-Bayt, and in their counter attack, they also began to revile Muawiya, Yazid and others. The extremists among the Shi'ites went on to revile the three caliphs, but the Imams are reported to have never encouraged them, rather condemned their actions. Ibn Sa'd writes that when asked if any one from among the Prophet's family spoke ill of the two caliphs, Imam Muhammad al-Bakir replied that, on the contrary, they had always loved them, followed them both and prayed for them (Tabaqat, 5:321).
Whatever is gleaned from the early Islamic history regarding tabarra, it remained a strict policy of the Ismailis in the light of the expressed guidance of the Imams not to curse or speak a single ill word against the Companions of the Prophet. Besides, the Ismailis condemn the system of tabarra.
In Bombay, Imam Sultan Muhammad Shah said to the jamat of Muscat on 21.12.1933 that, "Well done, you Muscat jamat are more courageous. The population of the Ithna Asharis is fifteen times bigger than you in the reign of the Sultan of Muscat, even then you have your reputation in the state, because of not creating troubles, and you do not revile three caliphs. I like it and wish it too." Besides, in Karachi, the Imam said to the jamat of Ormada on 26.1.1938 that, "Do not make hostility with the Shi'as and Sunnis, which weakens the Islam. You avoid it, who was Yazid? It is not our concern. We, the confessors of la ilaha ill-Allah Muhammad an-rasulillah are the brethren. Be aware of Yazid of present time. Don't break Islam. What is the benefit in reading the stories of a thousand years ago? Why reviling? It will promote dispute in Islam. Don't do anything to displease the Shi'as and Sunnis. The Sunni jamat gives respect to Muawiya. Why should we make enmity?"
On February 16, 1955, Imam Sultan Muhammad Shah sent his message for Islamic fraternity, which reads: "Though Ismailis have been always staunch and firm believers in the truth of their own faith in the Imamate Holy Succession, they have never, like some other sects, gone to the other extreme of condemning brother Muslims who have other interpretations of the Divine Message of our Holy Prophet. Ismailis have always believed and have been taught in each generation by their Imams that they hold the rightful interpretation of the succession to the Holy Prophet, but that is no reason why other Muslims, who believe differently, should not be accepted as brothers in Islam and dear in person and prayed for and never publicly or privately condemned, leave alone abused. I hope that in these days when the Muslims have to hold together in view of all the dangers, external and internal, from all quarters, I hope and believe and pray that the Ismailis may show their true Islamic charity in thought and prayer for the benefit and happiness of all Muslims, men, women and children of all sects."