It is narrated from Ammar Yasir that he said: I was with Amirul Momineen (a.s.) in the Battle of Ashira. The Imam said to me: O Abul Yaqzan, come let us check how the Bani Madlaj do at their water hole. I went with him and watched them for sometime but we felt sleepy and going inside a date orchard we went to sleep.
Suddenly the Holy Prophet (S) awoke us and was dusting the garments of Amirul Momineen (a.s.) saying: “O Abu Turab get up! And he said: O Abu Turab, shall I tell you about the worst of men?” “Yes, O Messenger of Allah (S).” The Holy Prophet (S) said: “The worst of men was Sarkhak Thamud who killed the she-camel of Prophet Salih (a.s.) and the worst man of this Ummah is one who will hit you here,” and he placed his hand on the head of Imam Ali (a.s.), “and will make this wet with blood,” saying this, he drew his hand on the beard of Imam Ali (a.s.).