He does mischief to himself who does mischief to another

He does mischief to himself who does mischief to another, and evil planned harms the plotter most. Hesiod. Works and Days. Section 238.

Image: Death of Sophonisba by Gaimbattista Pittoni before 1767 at the Pushkin Museum of Fine Arts courtesy of Wikimedia Commons.

Historical note: Sophonisba was a Carthaginian noblewoman who lived during the Second Punic War, and the daughter of Hasdrubal Gisco. She held influence over the Numidian political landscape, convincing king Syphax to change sides during the war, and later, in an act that became legendary, she poisoned herself rather than be humiliated in a Roman triumph.