It is narrated from Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) that he used to say: Some people think that when you go to relieve yourself, you should not face the Qiblah or Bayt al-Maqdis. Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) said: I climbed onto the roof of my house and I saw the Messenger of Allah (peace and blessings of Allah be upon him) relieving himself on two bricks, his face towards Bayt al-Maqdis. Then Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) said to Wasi’ bin Hibban: Perhaps you are among those people who pray sitting on their buttocks. Wasi’ said: I did not understand.
Imam Malik (may Allah have mercy on him) said in explanation of this statement: They are those who, in prostration, touch the ground and do not separate their backs from their buttocks.