Musannaf Ibn Abi Shayba 16:841

Abu Bakr narrated to us, he said: Ibn Idris narrated to us, from Yahya bin Abdullah bin Abi Qatadah, he said: The Prophet, may God bless him and grant him peace, joked with Abu Qatadah. He said: "Beware of your hair (jummah)." He said: "For you, there is a place for it, so cover it." He said to him after that: "Honor it." So he used to take care of it with oil (sudd) after that.