Hadith on urination

Some of you are perhaps familiar with the prohibition regarding urinating facing Mecca. Here is a hadith upon which this is based:

From al Bukhari

Volume 4, Book 53, Number 334 :

Narrated by 'Abdullah bin 'Umar

Once I went upstairs in Hafsa's house and saw the Prophet answering the call of nature with his back towards the Qibla and facing Sham.