حِصْنُ الْمُسْلِمِ
Hisn al-Muslim 24
Fortress of the Muslim (Hisn al-Muslim)
Concerning the athan (the call to prayer)
يُصَلِّي عَلَى النَّبِيِّ صلى الله عليه وسلم بَعْدَ فَرَاغِهِ مِنْ إِجَابَةِ الْمُؤَذِّنِ
After replying to the call of Mu'adh-dhin. you should recite in Arabic Allah's blessings on the Prophet (ﷺ). Reference: Muslim 1/288
Hisn al-Muslim, 24