Muwatta Imam Malik (Riwayat Ibn al-Qasim)

When the companion of the Prophet (peace be upon him), Abu Ayyub (al-Ansari, may Allah be pleased with him), was in Egypt, he said: By Allah! I do not know what I should do with these latrines facing the qiblah. And the Messenger of Allah (peace be upon him) said: "When any one of you goes to defecate or urinate, he should neither face the qiblah nor turn his back towards it with his private parts."

It is narrated from the father of an Ansari man that the Messenger of Allah, peace and blessings be upon him, forbade sitting facing the Qiblah while relieving oneself or urinating.

Sayyiduna Ibn Umar (may Allah be pleased with them both) used to say that people say: If you sit for relieving yourself, then neither face the Qiblah nor Bayt al-Maqdis. Abdullah ibn Umar (may Allah be pleased with them both) said: I had climbed onto the roof of my house and saw that the Messenger of Allah (peace and blessings be upon him) was relieving himself facing Bayt al-Maqdis. Then he (Ibn Umar) said (to Wasi‘ ibn Hibban, may Allah have mercy on him): Perhaps you are among those people who pray on their buttocks? (Wasi‘ ibn Hibban, may Allah have mercy on him, said:) I said: By Allah! I do not know. (Imam Malik said:) That is, the person who prostrates but does not rise above the ground, rather he remains clinging to the ground while prostrating.