Musannaf Ibn Abi Shayba 27:576

Affan narrated to us, he said: Hammad ibn Salamah narrated to us, he said: Thabit informed us, from Abu Uthman al-Nahdi, that the Messenger of Allah (may Allah bless him and grant him peace) said to al-Abbas: "Come here, for you are my equal (sanwi)."