Sunan an-Nasa'i 1378
سنن النسائي#1378Sahihأَخْبَرَنَا حُمَيْدُ بْنُ مَسْعَدَةَ، قَالَ حَدَّثَنَا بِشْرٌ، قَالَ حَدَّثَنَا دَاوُدُ بْنُ أَبِي هِنْدٍ، عَنْ أَبِي الزُّبَيْرِ، عَنْ جَابِرٍ، قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم " عَلَى كُلِّ رَجُلٍ مُسْلِمٍ فِي كُلِّ سَبْعَةِ أَيَّامٍ غُسْلُ يَوْمٍ وَهُوَ يَوْمُ الْجُمُعَةِ " .
It was narrated that Jabir said:"The Messenger of Allah (ﷺ) said: 'Every Muslim man has to perform Ghusl one day in every seven, and that is on Friday
Scholarly Authentication
The label above is the grade most of these scholars gave — one dissenting opinion no longer speaks for all of them. If any scholar calls a narration fabricated, that verdict is shown instead, whatever the others say. Each scholar's own wording:
Abu GhuddahSahih Lighairihi
Al-AlbaniSahih
Zubair Ali ZaiSahih
In-book reference: 14:15