A boy was born to one of our men, and he named him Qasim. The Ansar said, "We will not call you Abu Qasim, nor will we give you that pleasure."The Prophet ﷺ said, "The Ansar have done well. Name your children after my name, but do not take my kunya, for I am only a distributor."In Muslim's narration, "For I am Abu Qasim. I distribute among you."
ولد لرجل منا غلام فسماه القاسم. فقالت الأنصار: لا نكنك أبا القاسم ولا تنعمك عينا فقال النبي ﷺ: أحسنت الأنصار، سموا باسمي ولا تكنوا بكنيتي، فإنما أنا قاسم. وفي رواية مسلم: فإني أنا أبو القاسم أقسم بينكم.
Bukhari narrated it in the Book of the Fifth of War Spoils (3115), and Muslim narrated it in the Book of Manners (2133:5), both through the route of Amash, from Salim bin Abu Jaad, from Jabir bin Abdullah, who said, then he mentioned it.It has come in some narrations that he named the child "Muhammad," as found in Muslim (3:2133), but the more correct view is that it was "Qasim," because the objection raised by the Ansar against him only arose from the fact that naming his son Qasim would necessarily mean that he would come to be known by the kunya Abu Qasim.