Sahih al-Bukhari, Hadith 896 ⓘ

Narrated Abu Huraira: Allah's Messenger said "We are the last (to come amongst the nations) but (will be) the foremost on the Day of Resurrection. They were given the Holy Scripture before us and we were given the Quran after them. And this was the day (Friday) about which they differed and Allah gave us the guidance (for that). So tomorrow (i.e. Saturday) is the Jews' (day), and the day after tomorrow (i.e. Sunday) is the Christians'." The Prophet (p.b.u.h) remained silent (for a while) and then said, "It is obligatory for every Muslim that he should take a bath once in seven days, when he should wash his head and body."

حَدَّثَنَا مُسْلِمُ بْنُ إِبْرَاهِيمَ، قَالَ حَدَّثَنَا وُهَيْبٌ، قَالَ حَدَّثَنَا ابْنُ طَاوُسٍ، عَنْ أَبِيهِ، عَنْ أَبِي هُرَيْرَةَ، قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم ‏"‏ نَحْنُ الآخِرُونَ السَّابِقُونَ يَوْمَ الْقِيَامَةِ، أُوتُوا الْكِتَابَ مِنْ قَبْلِنَا، وَأُوتِينَاهُ مِنْ بَعْدِهِمْ، فَهَذَا الْيَوْمُ الَّذِي اخْتَلَفُوا فِيهِ فَهَدَانَا اللَّهُ، فَغَدًا لِلْيَهُودِ وَبَعْدَ غَدٍ لِلنَّصَارَى ‏"‏‏.‏ فَسَكَتَ‏.‏ ثُمَّ قَالَ ‏"‏ حَقٌّ عَلَى كُلِّ مُسْلِمٍ أَنْ يَغْتَسِلَ فِي كُلِّ سَبْعَةِ أَيَّامٍ يَوْمًا يَغْسِلُ فِيهِ رَأْسَهُ وَجَسَدَهُ ‏"‏‏.‏ ثُمَّ قَالَ ‏"‏ حَقٌّ عَلَى كُلِّ مُسْلِمٍ أَنْ يَغْتَسِلَ فِي كُلِّ سَبْعَةِ أَيَّامٍ يَوْمًا يَغْسِلُ فِيهِ رَأْسَهُ وَجَسَدَهُ ‏"‏‏.‏