Sayyiduna Ali (may Allah be pleased with him) said: Taking a ritual bath on Friday has been deemed recommended (mustahabb); it is not compulsory.
Imam al-Tabarani recorded this narration in al-Mu'jam al-Awsat, and its narrators are thiqat (trustworthy). (Allamah al-Haythami says:) I say: In the chapter before this one, a narration has already passed which indicates that taking a ritual bath on Friday is Sunnah. And Allah knows best.
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الصلاة / 3073