Musnad Ahmad 941:54

Muhammad ibn Bakr narrated to us, Yahya ibn Qays al-Ma'aribi informed us, he said: I asked 'Ata' about a dinar for a dinar with an excess between them, and a dirham for a dirham. He said: Ibn Abbas used to permit it. Ibn al-Zubayr said: "Ibn Abbas narrates what he did not hear from the Messenger of Allah, may Allah bless him and grant him peace." This reached Ibn Abbas, so he said: "I did not hear it from the Messenger of Allah, may Allah bless him and grant him peace, but Usamah ibn Zayd narrated to me that the Messenger of Allah, may Allah bless him and grant him peace, said: 'There is no usury (riba) except in deferred payment' or 'delay'."