When Hasan was born, he named him Hamza, and when Husayn was born, he named him after his uncle Jafar. He said, "The Messenger of Allah ﷺ called me and said, 'I have been commanded to change the names of these two.'"I replied, "Allah and His Messenger know best."So he named them Hasan and Husayn.
حدثنا زكريا بن عدي أنبأنا عبيد الله بن عمرو عن عبد الله بن محمد بن عقيل عن محمد بن علي
لما ولد الحسن سماه حمزة فلما ولد الحسين سماه بعمه جعفر قال فدعاني رسول الله ﷺ فقال إني أمرت أن أغير اسم هذين فقلت الله ورسوله أعلم فسماهما حسنا وحسينا