Musnad Abu Ya'la al-Mawsili 42:92

On the authority of Abu Sa’id, that the Messenger of Allah (may Allah bless him and grant him peace) saw a lagging behind among his companions. So he said to them: "Move forward and follow me, and let those who are behind you follow you. A people will not cease to lag behind until Allah, the Mighty and Majestic, puts them behind."