Hadith: When you go to a place to relieve yourselves, do not face or turn your back to the Qiblah (prayer direction); rather, turn towards the east or the west

عَنْ أَبِي أَيُّوبَ الأَنْصَارِيِّ رضي الله عنه أَنَّ النَّبِيَّ صَلَّى اللهُ عَلَيْهِ وَسَلَّمَ قَالَ:
«إِذَا أَتَيْتُمُ الغَائِطَ فَلاَ تَسْتَقْبِلُوا القِبْلَةَ، وَلاَ تَسْتَدْبِرُوهَا وَلَكِنْ شَرِّقُوا أَوْ غَرِّبُوا» قَالَ أَبُو أَيُّوبَ: فَقَدِمْنَا الشَّأْمَ فَوَجَدْنَا مَرَاحِيضَ بُنِيَتْ قِبَلَ القِبْلَةِ فَنَنْحَرِفُ، وَنَسْتَغْفِرُ اللَّهَ تَعَالَى.
[صحيح] - [متفق عليه] - [صحيح البخاري: 394]

Abu Ayyūb al-Ansāri (may Allah be pleased with him) reported that the Prophet (may Allah's peace and blessings be upon him) said:
"When you go to a place to relieve yourselves, do not face or turn your back to the Qiblah (prayer direction); rather, turn towards the east or the west." Abu Ayyūb said: We came to the Levant and found lavatories built in the direction of the Qiblah, so, we used to divert ourselves and ask forgiveness from Allah Almighty.
[Authentic hadith] - [Narrated by Bukhari & Muslim] - [Sahih Bukhari - 394]

Explanation

The Prophet (may Allah's peace and blessings be upon him) forbade the one who wants to relieve himself by urinating or defecating from facing the Qiblah and the direction of the Ka‘bah and from turning his back to it by making it behind his back. Rather, he should turn away from that direction towards the east or the west in case his Qiblah is like that of the people of Madīnah. Then, Abu Ayyūb (may Allah be pleased with him) reported that when they went to the Levant, they found the lavatories, which were set up for answering the call of nature, built facing the direction of the Ka‘bah. So, they used to divert their bodies from the Qiblah and seek forgiveness from Allah despite that.