It is narrated from Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) that an Ansari informed him that his father heard the Messenger of Allah (peace and blessings be upon him) forbidding facing the Qiblah at the time of relieving oneself.
Hadith Referenceالسنن المأثورة / باب ما جاء في الصلاة على الراحلة / 112
Hadith Takhrijمؤطا مالك ، رقم : 455 ، التمهيد لابن عبدالبر : 126/16، معرفة السنن والآثار للبيهقي : 193/1۔