Sahih al-Bukhari 898

Arabic

رَوَاهُ أَبَانُ بْنُ صَالِحٍ عَنْ مُجَاهِدٍ، عَنْ طَاوُسٍ، عَنْ أَبِي هُرَيْرَةَ، قَالَ قَالَ النَّبِيُّ صلى الله عليه وسلم ‏ "‏ لِلَّهِ تَعَالَى عَلَى كُلِّ مُسْلِمٍ حَقٌّ أَنْ يَغْتَسِلَ فِي كُلِّ سَبْعَةِ أَيَّامٍ يَوْمًا ‏"‏‏.‏

English translation

Narrated Abu Huraira through different narrators that the Prophet (ﷺ) said, "It is Allah's right on every Muslim that he should take a bath (at least) once in seven days

Reference: Sahih al-Bukhari 898, Book of Friday Prayer. English translation by Dr. Muhammad Muhsin Khan.