Sahih Muslim 849
Sahih Muslim · Book 7: The Book of Prayer - Friday · Perfume and siwak on Fridays
وَحَدَّثَنِي مُحَمَّدُ بْنُ حَاتِمٍ ، حَدَّثَنَا بَهْزٌ ، حَدَّثَنَا وُهَيْبٌ ، حَدَّثَنَا عَبْدُ اللَّهِ بْنُ طَاوُسٍ ، عَنْ أَبِيهِ ، عَنْ أَبِي هُرَيْرَةَ ، عَنِ النَّبِيِّ صلى الله عليه وسلم قَالَ " حَقٌّ لِلَّهِ عَلَى كُلِّ مُسْلِمٍ أَنْ يَغْتَسِلَ فِي كُلِّ سَبْعَةِ أَيَّامٍ يَغْسِلُ رَأْسَهُ وَجَسَدَهُ " .
Abu Huraira reported that the Messenger of Allah (ﷺ) said. it is the right of Allah upon every Muslim that he should take a bath (at least) on one day (Friday) during the seven days (of the week) and he should wash his head and body.