Ali bin Ibrahim says that people asked Imam Ja’far Sadiq (a.s.) when Imam Ali (a.s.) confronted Talha bin Abi Talha, why he referred to him as Khasam ‘one who beats the valiant’? Imam Ja’far Sadiq (a.s.) said: “When the Holy Prophet (S) was in Mecca, no one dared to harm him due to the awe of Abu Talib but they incited their boys to harass the Prophet.
So when he left home, they used to pelt him with stones and throw garbage on him. When Amirul Momineen (a.s.) came to know about it, he said: O Messenger of Allah (S), take me along when you go out so that I may keep you safe from the trouble of those boys.” After that whenever the Holy Prophet (S) left home, he used to take Imam Ali (a.s.) along. When the boys used to target the Prophet, Amirul Momineen (a.s.) used to hit them and wounded their noses, ears and mouths, and they used to go back to their father and say: “Khasamna Aliyyun” that is Ali has wounded us. That is why they used to refer to him as ‘Khasam’.