Abū-Bakr saw him praying with great dedication and did not...
Abū-Bakr saw him praying with great dedication and did not like to kill him and returned. Then the Prophet (a.s) asked `Umar to execute him. He too saw him offering prayer and returned and said that he is a pious person and he could not kill him. In the end the Prophet (a.s) deputed `Ali (a.s), but by that time Dhul-Khuwaysirah had already left from there. The Imam (a.s) returned and reported to the Prophet (a.s) that he had gone away.
The Prophet (a.s) said that if he was killed today the mischief could have been nipped in the bud. He is a member of that group who will get out of the faith in a manner the arrow escapes from the bow! The Khawarij were the nomads of Arabia who naturally had all the traits of the Bedouin. By instinct, they were agitators and liked to fight and kill. After the Prophet (a.s), they were pushed into many a war.
Thus, they were so much involved in fighting that when there was no battle to fight, they would fight amongst themselves. These warlike activities did not give them time to study the niceties of the Faith or to take any effect of the moral values promoted by it. After the conquest of Iraq, when the foundation for the cities of al-Kūfah and al-Basrah were laid with the purpose of guarding the boundaries of the realm, these rough Bedouin people were settled in these places.
They settled down here for better prospects but despite coming to live in the cities, they continued with their old diehard traits. When Amir al-Mu’minin (a.s) wanted an army to fight against the enemy, these people, who were veterans of many a battle, rose to a man on the call of the Imam (a.s). Their willingness was not on the basis of principle or for upholding the Truth. Their motivation was only their instinct and craving for fighting and material gains.
Among the Khawarij mostly there were men from Banū-Tamim and the gallivants of Arabia. Therefore, `Abdullah ibn Abaz, `Urwah ibn al-`Adiyah, Mustaradd ibn Sa`d, Abū-Bilal Mirdas ibn al-`Adiyah, Mus`ir ibn Fadki etc belonged to the tribe of Banū-Tamim. Before Islam, the Banū-Tamim were fire worshippers and because of penury and hardships they used to bury their daughters alive. Therefore, Qays ibn `Asim al-Tamimi said to the Prophet (a.s) on embracing Islam, “O Allah’s Messenger (a.s)!
During the days of ignorance I have buried eight of my daughters alive!” Even after accepting Islam their wild instinct remained latent in their psyche and came out from time to time when the occasion demanded.