Musannaf Ibn Abi Shayba 3:598

Abu Mu'awiyah narrated to us, from Musa ibn Muslim, who said: A man came to pray while Tawus was sitting. He began not to complete the bowing (ruku') nor the prostration (sujud). Some of the people said: "This one has no prayer." Tawus said: "Desist. It is written for him from it according to what he performed."