Anas reported that person at Baqi' called another person as" Abu'l- Qasim," and Allah's Messenger (may peace be upon him) turned towards him. He (the person who had uttered these words) said: Messenger of Allah, I did not mean you, but I called such and such (person), whereupon Allah's Messenger (may peace be upon him) said: You may call yourself by my name, but not by my kunya.