Sayyiduna Abu Hurayrah (may Allah be pleased with him) said that the Messenger of Allah (peace and blessings be upon him) said: "When three people are on a journey, let them appoint one of them as their leader (amir)." Nafi' said: So I said to Abu Salamah: You are our leader.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الحج / 10349