Sayyiduna Abdullah bin Amr al-Ajlani (may Allah be pleased with him) narrates from his father that the Messenger of Allah (peace and blessings be upon him) forbade facing either of the two qiblahs (Bayt al-Maqdis and the Ka'bah) while relieving oneself or urinating.
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 14073