When Amir al-mu'minin approached Basrah an Arab met him and spoke to him, as he had been sent to him by a group of people of Basrah to enquire from him on their behalf position vis--vis the people of Jamal. Amir al-mu'minin explained to him his position with respect to them, from which he was convinced that Amir al-mu'minin was in the right. Then Amir al-mu'minin asked him to swear allegiance, but he replied "I am just a message carrier of a people and shall not do anything until I get back to them." Upon this Amir al-mu'minin said to him:
If those at your back send you as a forerunner to search out a rain-fed area for them, and you return to them and apprise them of greenery and water but they disagree with you and go towards dry and barren land, what would you do then? He said: I would leave them and go towards greenery and water. Amir al-mu'minin then said: So then extend your hand.
This man related that: By Allah, by such a clear argument I could not refrain from swearing allegiance to Amir al-mu'minin.
This man was know as Kulayb al-Jarmi.
(1) Al-Waqidi, al-Jamal, in al-Mufid, al-Jamal, 156;
(2) al-Tabari, Ta'rikh, V, 192, events of 36 H.;