Musnad Abu Ya'la al-Mawsili 115:307

Ubayd Allah narrated to us, Harami narrated to us, Shu'bah narrated to us, from Qatadah, from Anas, who said: The Messenger of Allah (may Allah bless him and grant him peace) granted a concession to Abd al-Rahman ibn Awf and al-Zubayr ibn al-Awwam regarding silk, due to an itch that they both had.