Musnad Ahmad 388:1

Sufyan narrated to us, he said: Mansur narrated to me, from his maternal uncle Musafi’, from Safiyyah bint Shaybah, the mother of Mansur, who said: A woman from Banu Sulaym, who delivered most of the people of our house, informed me that the Messenger of Allah (ﷺ) sent for Uthman ibn Talha. And he said once: She asked Uthman ibn Talha, "Why did the Prophet (ﷺ) call you?" He said: "I had seen the two horns of the ram when I entered the House (the Kaaba), and I forgot to order you to cover them. So cover them, for it is not fitting that there be anything in the House that distracts the one praying." Sufyan said: The two horns of the ram remained in the House until the House burned down, and they burned with it.