Musnad Ahmad 1239:2

Sufyan said another time: Kathir ibn Kathir ibn al-Muttalib ibn Abi Wada'ah narrated to me, from someone who heard his grandfather say: "I saw the Messenger of Allah (peace and blessings of Allah be upon him) praying near the gate of Banu Sahm, and the people were passing in front of him, and there was no sutrah between him and the Ka'bah."