وَ رَوَى زُرَارَةُ عَنْ أَبِي جَعْفَرٍ عَلَيْهِ اَلسَّلاَمُ أَنَّهُ قَالَ: «لاَ يُجْزِيكَ مِنَ اَلْأَذَانِ إِلاَّ مَا أَسْمَعْتَ نَفْسَكَ أَوْ فَهِمْتَهُ وَ أَفْصِحْ بِالْأَلِفِ وَ اَلْهَاءِ وَ صَلِّ عَلَى اَلنَّبِيِّ وَ آلِهِ صَلَوَاتُ اَللَّهِ عَلَيْهِمْ كُلَّمَا ذَكَرْتَهُ أَوْ ذَكَرَهُ ذَاكِرٌ عِنْدَكَ فِي أَذَانٍ أَوْ غَيْرِهِ وَ كُلَّمَا اِشْتَدَّ صَوْتُكَ مِنْ غَيْرِ أَنْ تُجْهِدَ نَفْسَكَ كَانَ مَنْ يَسْمَعُ أَكْثَرَ وَ كَانَ أَجْرُكَ فِي ذَلِكَ أَعْظَمَ.
Zurarah narrated from Imam Muhammad ibn Ali Al-Baqir (a.s) that He said: "The adhan is not sufficient for you unless you hear it yourself or understand it. Clearly articulate the 'alif' and 'ha'." Send blessings upon the Prophet and his family (a.s) whenever you mention him or hear someone mention him, whether during the adhan or outside of it. The louder your voice, without straining yourself, the more people will hear, and your reward will be greater."