Musnad Ahmad 1129:16

Yunus ibn Muhammad narrated to us, Ayyub narrated to us, from Qays, from his father, who said: I came to the Prophet, may Allah bless him and grant him peace, while his companions were building the mosque. He said: It was as if he did not like their work. He said: So I took the shovel and mixed the clay with it. It was as if he liked my taking of the shovel and my work, so he said: "Leave the Hanafite and the clay, for he is the best of you at handling the clay."