Abdullah b. Umar is reported to have said that The Messenger of Allah (may peace be up on him) was standing on the pulpit when he said this:
He who comes for Jumu'a he should take a bath.
Reference: Sahih Muslim 844 b
In-book reference: Book 7, Hadith 2
USC-MSA web (English) reference(deprecated numbering scheme): Book 4, Hadith 1833