Musnad Abu Ya'la al-Mawsili 117:212

Mujahid ibn Musa narrated to us, Yazid ibn Harun narrated to us, Hammad ibn Salamah narrated to us, from Thabit, from Anas, who said: When the Messenger of Allah (peace be upon him) migrated, he would ride, and Abu Bakr was behind him. Abu Bakr al-Siddiq knew the road due to his frequent traveling to al-Sham. He would pass by people, and they would say, "Who is this with you?" He would say, "A guide who guides me." When they drew near to Medina, they sent to the people who had accepted Islam from the Ansar, to Abu Umamah and his companions. They went out to them and said, "Enter, safe and obeyed." So they entered. Anas said: I have never seen a day more radiant or more beautiful than the day the Messenger of Allah (peace be upon him) and Abu Bakr entered Medina.