عَنْ أَبِي سَعِيدٍ الْخُدْرِيِّ رَضِيَ اللَّهُ عَنْهُ أَنَّ رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَآلِهِ وَسَلَّمَ قَالَ: ((لَوْ يَعْلَمُ النَّاسُ مَا فِي التَّأْذِينِ لَتَضَارَبُوا عَلَيْهِ بِالسُّيُوفِ))
It is narrated from Sayyiduna Abu Sa'id Khudri, may Allah be pleased with him, that the Messenger of Allah, peace and blessings be upon him, said: If people knew what (reward and merit) there is in calling the Adhan, they would fight each other with swords for it (to attain that reward).