Musannaf Ibn Abi Shayba 3:5428

Waki’ narrated to us, he said: Sharik narrated to us, from Dithar al-Qattan, from al-Nu’man ibn Naqid, that Ali went out and saw a people praying the Duha (forenoon) prayer at the rising of the sun. He said: "What is the matter with them? May Allah slaughter them, as they have slaughtered it (the prayer). Why did they not leave it until it was at the distance of two spears? Then they would have prayed, for that is the prayer of the oft-returning (al-awwabin)."