Musnad Ahmad 32:147

Sufyan narrated to us, from ‘Asim, from Anas, who said: "The Messenger of Allah (ﷺ) did not grieve over any detachment [of soldiers] as he grieved over them; they used to be called 'the Qurra' (the reciters)." Sufyan said: "It was revealed concerning them: 'Convey to our people on our behalf that we have become pleased [with our Lord], and He has become pleased with us.'" It was said to Sufyan: "Concerning whom was it revealed?" He said: "Concerning the people of Bi'r Ma'unah."