Musnad Abu Ya'la al-Mawsili 153:102

Muhammad ibn Abdullah ibn Numayr narrated to us, Ishaq ibn Sulayman al-Razi narrated to us, Hanzalah narrated to us, he said: I heard Salim, he said: I heard Ibn Umar saying: The Messenger of Allah (peace and blessings of Allah be upon him) said: "For the interior of the son of Adam to be filled with pus is better for him than for it to be filled with poetry."