Reference: The Verdicts of the Permanent Committee Volume 11, Page 110, Fatwa No.12084
Question: Is our appointing an ameer (“group” leader) during the Hajj journey permissible or not?
Response: It is legislated for a group who are travelling, if they are three or more that they appoint one of them as the leader. It was reported in the Sunan of Abu Daawood on the authority of Abu Sa’eed al-Khudree (may Allah be pleased with him), that the Messenger of Allah (peace and blessing of Allah be upon him) said,: “When three set out on a journey, then they should appoint one of them as the ameer (leader)” [Abu Daawood # 2608]. This way their affairs will be agreed upon, there will be no division in their opinions and they will be no disagreement.
And with Allaah lies all the success, and may the prayers and blessings of Allaah be upon our Prophet Muhammad his family and his companions.