Sayyiduna Jabir narrates this saying of the Prophet (peace and blessings be upon him): "Taking a ritual bath (ghusl) on Friday is obligatory upon every adult."
Imam al-Tabarani recorded this narration in al-Mu'jam al-Awsat. Its chain contains a narrator, Abdullah bin Muhammad bin Sa'id bin Abi Maryam, who is extremely da'if (weak).
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الصلاة / 3052