Musnad Ahmad #906

It was narrated that ‘Ali (رضي الله عنه) said: When al-Hasan was born, the Messenger of Allah (ﷺ) came and said: “Show me my son; what did you name him?` I said: I named him Harb . He said: `Rather he is Hasan.” When al-Husain was born, he said: `Show me my son; what did you name him?` I said: I named him Harb, He said: `Rather he is Husain.” When the third one was born, the Prophet (ﷺ) said: `Show me my son; what did you name him?` I said: Harb, He said: “Rather. he is Muhassin.” Then he said: “I have named them after the fashion of the sons of Haroon, Shabbar and Shabeer and Mushabbir.”