Musnad Ahmad 457:35

Abu Mu'awiyah narrated to us, he said: Al-A'mash narrated to us, from Isma'il ibn Raja', from Aws ibn Dam'aj, from Abu Mas'ud al-Ansari, who said: The Messenger of Allah, peace and blessings of Allah be upon him, said: "The people should be led in prayer by the one among them who is most proficient in the Book of Allah the Exalted. If they are equal in recitation, then the one most knowledgeable of the Sunnah. If they are equal in the Sunnah, then the one who migrated earliest. If they are equal in migration, then the oldest of them in age. And a man should not lead another in prayer in his place of authority, nor should he sit in his place of honor in his house, unless he gives permission."