Musnad Abu Ya'la al-Mawsili 3:83

Ubayd Allah narrated to us, Yazid bin Harun narrated to us, al-Mas'udi informed us, from Habib bin Abi Thabit, from Abu al-Hayyaj, who said: Ali said: "Shall I not send you upon that which the Messenger of Allah (ﷺ) sent me upon? Do not leave a grave without leveling it, and do not leave an image without effacing it."