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. (ID)
Reference (ID): Sahih Muslim 844 b (ID)
In-book reference (ID): Book 7, Hadith 2 (ID)
USC-MSA web (English) reference(deprecated numbering scheme): Book 4, Hadith 1833 (ID)