Riyad as-Salihin 17:177

Abul-Haiyaj Haiyan bin Husain said:

'Ali bin Abu Talib (May Allah be pleased with him) said to me: "Shall I not send you to do a task that the Messenger of Allah (ﷺ) had assigned to me? Spare no portrait unwiped out, and leave not a high grave unlevelled." [Muslim] .