Hate.

"Hate is too great a burden to bear. It injures the hater more than it injures the hated." — Corretta Scott King

"A rattlesnake, if cornered, will becomes so angry it will bite itself. That is exactly what the harboring of hate and resentment against others is – a biting of oneself. We think we are harming others in holding these spites and hates, but the deeper harm is to ourselves." — E. Stanley Jones

And my favorite is from a short Japanese tale called "A Model Demon." This part inspired my 'Bind' triptych. I can't believe I didn't put it in that post:

"My rage burns as fiercely as ever, but my enemy's descendants are gone! Now I'm alone with the pain of this fire that nothing will extinguish. If I'd never felt this way I might even have been born into paradise, but hate has brought me an eternity of suffering. 
A grudge against someone else is just like a grudge against yourself. I wish I'd known, I only wish I'd known!"

8 x 12" watercolor paper.
Acrylic, graphite, and digital.