(11) CHAPTER. While urinating or defecating, never face the Qiblah except when you are screened by a building or a wall or something like that.
Narrated Abu Aiyub Al-Ansari: Allah's Apostle said, If anyone of you goes to an open space for answering the call of nature he should neither face nor turn his back towards the Qibla; he should either face the east or the west.
Authentic