Sahih Bukhari
Ablutions (Wudu)
Volume: 001 / Book Number: 004 / Hadith Number: 147
Narrated 'Abdullah bin 'Umar:
People say, "Whenever you sit for answering the call of nature, you should not face the Qibla or Bait-ulMaqdis (Jerusalem)." I told them. "Once I went up the roof of our house and I saw Allah's Apostle answering the call of nature while sitting on two bricks facing Bait-ul-Maqdis (Jerusalem) (but there was a screen covering him. ' (FatehAl-Bari, Page 258, Vol. 1).