Sahih al-Bukhari 858
Sahih al-Bukhari · Book 10: Call to Prayers (Adhaan) · The ablution for boys (youngsters). When they should perform Ghusl (take a bath) and Tuhur (purification). Their attendance at congregational prayers and their rows in the prayers.
Narrated Abu Sa`id Al-Khudri:
حَدَّثَنَا عَلِيُّ بْنُ عَبْدِ اللَّهِ ، قَالَ حَدَّثَنَا سُفْيَانُ ، قَالَ حَدَّثَنِي صَفْوَانُ بْنُ سُلَيْمٍ ، عَنْ عَطَاءِ بْنِ يَسَارٍ ، عَنْ أَبِي سَعِيدٍ الْخُدْرِيِّ ، عَنِ النَّبِيِّ صلى الله عليه وسلم قَالَ " الْغُسْلُ يَوْمَ الْجُمُعَةِ وَاجِبٌ عَلَى كُلِّ مُحْتَلِمٍ " .
The Prophet (ﷺ) said, "Ghusl (taking a bath) on Friday is compulsory for every Muslim reaching the age of puberty."