Musnad Ahmad 32:933

Yahya narrated to us, from Humayd, from Anas, that the Banu Salama wanted to move from their dwellings to near the mosque. The Messenger of Allah (may Allah bless him and grant him peace) disliked that the mosque should be left empty, so he said: "O Banu Salama, do you not seek the reward for your footsteps?" So they stayed. Abdullah ibn Ahmad said: My father said: "Yahya ibn Sa'id erred in it; it is only: 'that Medina should be left empty,' but Yahya said: 'the mosque.' And my father struck through it here, and he had narrated it to us in the book of Yahya ibn Sa'id."