It was narrated that Malik bin Al-Huwairith said:

"I came to the Prophet ﷺ with a cousin of mine" - on an another occasion he said: "with a companion of mine" - "and he said: 'When the two of you travel, call the Adhan and the Iqamah, and let the older of you lead the prayer.'"

أَخْبَرَنَا حَاجِبُ بْنُ سُلَيْمَانَ، عَنْ وَكِيعٍ، عَنْ سُفْيَانَ، عَنْ خَالِدٍ الْحَذَّاءِ، عَنْ أَبِي قِلاَبَةَ، عَنْ مَالِكِ بْنِ الْحُوَيْرِثِ، قَالَ أَتَيْتُ النَّبِيَّ ﷺ أَنَا وَابْنُ عَمٍّ لِي وَقَالَ مَرَّةً أُخْرَى أَنَا وَصَاحِبٌ لِي فَقَالَ " إِذَا سَافَرْتُمَا فَأَذِّنَا وَأَقِيمَا وَلْيَؤُمَّكُمَا أَكْبَرُكُمَا " .