That his father said: "I saw the Messenger of Allah ﷺ say the Adhan in the ear of Al-Hasan bin 'Ali - when he was born to Fatimah - the Adhan of Salat."
رَأَيْتُ رَسُولَ اللَّهِ ﷺ أَذَّنَ فِي أُذُنِ الْحَسَنِ بْنِ عَلِيٍّ حِينَ وَلَدَتْهُ فَاطِمَةُ بِالصَّلاَةِ