Sunan Ibn Majah, Volume 1, Book 3, Hadith 728 (DarusSalam) ⓘ
It was narrated from Ibn 'Umar that: The Messenger of Allah said: "Whoever calls the Adhan for twelve years, he will be guaranteed Paradise, and for each day sixty Hasanat (good deeds) will be recorded for him by virtue of his Adhan, and thirty Hasanat by virtue of his Iqamah."
حَدَّثَنَا مُحَمَّدُ بْنُ يَحْيَى، وَالْحَسَنُ بْنُ عَلِيٍّ الْخَلاَّلُ، قَالاَ حَدَّثَنَا عَبْدُ اللَّهِ بْنُ صَالِحٍ، حَدَّثَنَا يَحْيَى بْنُ أَيُّوبَ، عَنِ ابْنِ جُرَيْجٍ، عَنْ نَافِعٍ، عَنِ ابْنِ عُمَرَ، أَنَّ رَسُولَ اللَّهِ ـ صلى الله عليه وسلم ـ قَالَ " مَنْ أَذَّنَ ثِنْتَىْ عَشْرَةَ سَنَةً وَجَبَتْ لَهُ الْجَنَّةُ وَكُتِبَ لَهُ بِتَأْذِينِهِ فِي كُلِّ يَوْمٍ سِتُّونَ حَسَنَةً وَلِكُلِّ إِقَامَةٍ ثَلاَثُونَ حَسَنَةً " .
also referenced under: Hadith 728 (Reference) & Book 3, Hadith 23 (In-Book)