Musannaf Ibn Abi Shayba 28:397

Abu Bakr ibn Ayyash narrated to us, he said: Mu'awiyah ibn Hisham narrated to us, he said: Sufyan narrated to us, from Iyad ibn Laqit, from al-Bara' ibn Qays, he said: Umar ibn al-Khattab sent me to Salman ibn Rabi'ah, commanding him to break his fast while he was besieging [a city].