Sunan an-Nasai 14755
In-book no 19أَخْبَرَنَا إِسْحَاقُ بْنُ إِبْرَاهِيمَ، قَالَ أَنْبَأَنَا إِسْمَاعِيلُ، عَنْ عَبْدِ الْعَزِيزِ بْنِ صُهَيْبٍ، عَنْ أَنَسِ بْنِ مَالِكٍ، قَالَ كَانَ رَسُولُ اللَّهِ صلى الله عليه وسلم إِذَا دَخَلَ الْخَلاَءَ قَالَ " اللَّهُمَّ إِنِّي أَعُوذُ بِكَ مِنَ الْخُبُثِ وَالْخَبَائِثِ " .
It was narrated that Anas bin Malik said: "The Messenger of Allah (ﷺ) entered Al-Khala' (the toilet) and said: 'Allahumma inni a'uthu bika min al-khubuthi wal-khaba'ith (O Allah, I seek refuge with You from male and female devils)." See Ma'alam As-Sunan by Al-Khattabi. And Al-Khala' is the area one relieves oneself in. It refers to outside or other than that, it should not be understood to mean toilet only.