Musannaf Ibn Abi Shayba 3:2207

Ibn ‘Uyaynah narrated to us, from Mansur ibn Safiyyah, from the maternal aunt of Musafi’, from the sister of Safiyyah, the mother of Mansur, who said: A woman from the people of the house, from Banu Sulaym, informed me. She said: I said to ‘Uthman ibn Talhah, "Why did the Messenger of Allah (ﷺ) call you when he came out of the House (the Ka'bah)?" He said: He said, "I saw the two horns of the ram, and I forgot to order you to cover them, for it is not fitting that there should be in the House anything that distracts the one praying."