Riyad as-Salihin 740 — The Book About the Etiquette of Eating

Salama bin Al-Akwa` Narrated from:

A man ate with his left hand in the presence of Messenger of Allah (ﷺ), whereupon he said, "Eat with your right hand." The man said: "I cannot do that." Thereupon he (the Prophet (ﷺ)) 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 afterwards. [Muslim].