Musannaf Ibn Abi Shayba 27:721

Affan narrated to us, he said: Hammad bin Zayd narrated to us, from Abd al-Rahman bin Abi Salamah, he said: A man narrated to me from Sa'id al-Sarraf—and he is from Sa'id al-Sarraf—from Ishaq bin Sa'd bin Ubadah, from his father, he said: The Messenger of Allah (may Allah bless him and grant him peace) said: "Indeed, this tribe of the Ansar is a trial; loving them is faith, and hating them is hypocrisy."