Musnad Abu Ya'la al-Mawsili 6:109

Abu Khaythama narrated to us, Abu ‘Amir al-‘Aqdi narrated to us, from Shu’bah, from Qatadah, from Yunus ibn Jubayr, from Muhammad ibn Sa’d, from his father Sa’d ibn Abi Waqqas, from the Prophet (peace and blessings of Allah be upon him), who said: "For the interior of one of you to be filled with pus until it consumes him is better for him than to be filled with poetry."