Sahih al-Bukhari, Volume 1, Book 11, Hadith 627 (USC-MSA) ⓘ
Narrated Malik bin Huwairith: 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."
حَدَّثَنَا مُسَدَّدٌ، قَالَ حَدَّثَنَا يَزِيدُ بْنُ زُرَيْعٍ، قَالَ حَدَّثَنَا خَالِدٌ، عَنْ أَبِي قِلاَبَةَ، عَنْ مَالِكِ بْنِ الْحُوَيْرِثِ، عَنِ النَّبِيِّ صلى الله عليه وسلم قَالَ " إِذَا حَضَرَتِ الصَّلاَةُ فَأَذِّنَا وَأَقِيمَا، ثُمَّ لِيَؤُمَّكُمَا أَكْبَرُكُمَا " .
also referenced under: Book 10, Hadith 52 (In-Book) & Hadith 658 (DarusSalam)