Sunan Ibn Majah
324
Daif+3

It was narrated that 'Aishah said:"Mention was made in the presence of the Messenger of Allah of some people who did not like to face towards the Qiblah with their private parts. He said: 'I think that they do that. Turn my seat (in the toilet) to face the Qiblah.'" (Da'if) Another chain with similar wording

DaifAl-Albani
DaifMuhammad Fouad Abd al-Baqi