Sunan an Nasai
The Book of the Adhan (The Call to Prayer)
Hadith #44
7.44
أَخْبَرَنَا عَلِيُّ بْنُ حُجْرٍ، قَالَ أَنْبَأَنَا إِسْمَاعِيلُ، عَنْ خَالِدٍ الْحَذَّاءِ، عَنْ أَبِي قِلاَبَةَ، عَنْ مَالِكِ بْنِ الْحُوَيْرِثِ، قَالَ قَالَ لِي رَسُولُ اللَّهِ صلى الله عليه وسلم وَلِصَاحِبٍ لِي " إِذَا حَضَرَتِ الصَّلاَةُ فَأَذِّنَا ثُمَّ أَقِيمَا ثُمَّ لْيَؤُمَّكُمَا أَحَدُكُمَا " .
It was narrated that Malik bin Al-Huwayrith said:"The Messenger of Allah (S.A.W) said to me and to a companion of mine: 'When the time for prayer comes, let the two of you call the Adhan then the two of you say Iqamah, then let one of you lead the prayer