Musannaf Ibn Abi Shayba 3:4719

Mu'adh ibn Mu'adh narrated to us, from Abu Hurrah, who said: I and Abdullah ibn Humayd entered a mosque, and [the people] had already prayed in it. He said: "Will you not come so that we may pray in a congregation?" I said: "Indeed, some of them have disliked that." He said: "My father used to see no harm in that."