Nafi' narrates from Ibn Umar (may Allah be pleased with them both) that when the first Muhajirun came, they stopped at al-Usbah before the arrival of the Prophet (peace and blessings be upon him), and Salim (may Allah be pleased with him), the freed slave of Abu Hudhayfah (may Allah be pleased with him), used to lead them in prayer; he knew the most Qur'an.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 5123