Hadith 3:235
Abu Huraira reported God’s messenger as saying, “It is a duty for every Muslim to bathe once a week, washing his head and his body.” (Bukhari and Muslim.)
وَعَنْ أَبِي هُرَيْرَةَ رَضِيَ اللَّهُ عَنْهُ قَالَ: قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ: «حَقُّ عَلَى كُلِّ مُسْلِمٍ أَنْ يَغْتَسِلَ فِي كُلِّ سَبْعَةِ أَيَّامٍ يَوْمًا يَغْسِلُ فِيهِ رَأسه وَجَسَده»
Original Reference: Mishkat al-Masabih 539