This is no doubt a massive butchery of the original quote, taken from my memory of the book "The Buddha, Geoff and Me", but I hope the sentiment carries through regardless.
Every day, the Buddha would walk through town. While walking, he would pass a man, who deeply despised the Buddha and everything he stood for. He would hurl insults at the Buddha, the most vile and reprehensible accusations. Every day, the Buddha would just nod and smile towards the man, then carry on his walk. Every day, the man would say the worst thing he could think of.
One day, the man did not say anything horrible. He stood in front of the Buddha, stopping him, and asked him, "I say all these things to you every day, why don't you react? Do you not understand how much I think you're a horrible person?"
The Buddha replied, after a moment, "If I gave you a gift, would you accept it?"
The man said, "No, of course not. You're the worst, I wouldn't accept anything from you."
"Then who would the gift belong to, would it be yours?"
"No, it's not mine, you have to keep it!"
The Buddha replied: "Such is the way with your anger. If I do not accept it, then it belongs to you, and you alone."
Hah! That's quite clever, thank you for sharing it here!