Musannaf Ibn Abi Shayba 1:1602

Zayd ibn al-Hubab narrated to us, from Malik ibn Anas, from Ishaq ibn Abdullah ibn Abi Talhah, from Rafi ibn Ishaq, the freed slave of Talhah, who said: I heard Abu Ayyub say: "What shall I do with these garments (karabis)? For the Messenger of Allah (peace and blessings of Allah be upon him) said: 'When one of you goes for defecation or urination, do not face the Qibla—or he said: the Kaaba—with your private parts.'"