Prophet said (to two persons), "Whenever the prayer time becomes due, you should pronounce Adhan and then Iqama and the older of you should lead the prayer." (Using translation from Bukhārī 658)   

قَالَ لِي رَسُولُ اللهِ ﷺ وَلِصَاحِبٍ لِي «إِذَا حَضَرَتِ الصَّلَاةُ فَأَذِّنَا ثُمَّ أَقِيمَا ثُمَّ لِيَؤُمَّكُمَا أَكْبَرُكُمَا»