Musnad Ahmad 1153:1819

Bahz narrated to us, he said: Hammad ibn Salamah narrated to us, Khalid al-Hadhdha’ narrated to us, from Khalid ibn Abi al-Salt, who said: They mentioned in the presence of Umar ibn Abd al-Aziz, may Allah have mercy on him, the matter of facing the Qiblah with one’s private parts. 'Arak ibn Malik said: Aisha said: They mentioned in the presence of the Messenger of Allah, peace and blessings of Allah be upon him, that some people dislike that. He said: So he said: "They have already done it. Turn my seat towards the Qiblah."