بُلُوغُ الْمَرَامِ
Bulugh al-Maram 215
The Book of Prayer
وَعَنْ أَبِي سَعِيدٍ - رضى الله عنه - عَنْ اَلنَّبِيِّ - صلى الله عليه وسلم -{ اَلْأَرْضُ كُلُّهَا مَسْجِدٌ إِلَّا اَلْمَقْبَرَةَ وَالْحَمَّامَ } رَوَاهُ اَلتِّرْمِذِيُّ , وَلَهُ عِلَّةٌ . [1] .
Narrated Abu Sa'id al-Khudri (RA): The Prophet (ﷺ) said: "The whole earth is a mosque (to pray on) except a graveyard and a toilet." [Reported by at-Tirmidhi and it has an 'Illa (a defect)].
Sunnah.com reference: Book 2, Hadith 79