Sahih Muslim | Book 23 | Hadith Number 5011

Narrated by Salama b. Akwa'
Salama b. Akwa' reported on the authority of his father that a person ate in the presence of Allah's Messenger (may peace be upon him) with his left hand, whereupon he said: Eat with your right hand. He said: I cannot do that, whereupon he (the Holy Prophet) said: May you not be able to do that. It was vanity that prevented him from doing it, and he could not raise it (the right hand) up to his mouth.