Hadith about Friday Prayer.

Bukhari :: Book 2 :: Volume 13 :: Hadith/12

Narrated Abu Huraira:

Allah's Apostle said, "If I had not found it hard for my followers or the people, I would have ordered them to clean their teeth with Siwak for every prayer."

Bukhari :: Book 2 :: Volume 13 :: Hadith 13

Narrated Anas:

Allah's Apostle I said, "I have told you repeatedly to (use) the Siwak. (The Prophet put emphasis on the use of the Siwak.)