Yahya related to me from Malik from Said ibn Abi Said al-Maqburithat Abu Hurayra used to say, "Doing ghusl as prescribed for majorritual impurity is incumbent (wajib) on the day of jumua on every malewho has reached puberty."
USC-MSA web (English) reference: Book 5, Hadith 2
Arabic reference: Book 5, Hadith 227