While the Prophet was in the market, somebody, called, O ...

Hadith 3:331

Narrated Anas bin Malik:

While the Prophet was in the market, somebody, called, "O Abu-l-Qasim." The Prophet turned to him. The man said, "I have called to this (i.e. another man)." The Prophet said, "Name yourselves by my name but not by my Kuniya (name)." (In Arabic world it is the custom to call the man as the father of his eldest son, e.g. Abu-l-Qasim.)

(See Hadith No. 737, Vol. 4)