One night Ravana found the apsara Rambha wandering in the woods.
She was very beautiful, and Ravana burned with lust. He grabbed her and whispered, "How lucky for you we have met!"
"Stop it!" she shouted, fighting back. "You are my elder relative, my uncle-in-law! My husband Nalakubara is the son of Kubera. He's your nephew. Let me go!"
But Ravana knew no shame, and he brutally raped Rambha that night.
When Rambha told Nalakubara what Ravana had done, he cursed his uncle. "If Ravana ever touches another woman against her will, his head will split into a thousand pieces."
Inspired by: The Ramayana (Uttara Kanda, 26).
Notes: Nalakubara is the son of Ravana's half-brother Kubera; for more about Kubera, see Wikipedia. In the Yuddha Kanda, sarga 13, Ravana himself tells a story about raping an apsara named Punjikasthala, and when she told Brahma what Ravana had done, Brahma cursed Ravana: "From today onwards, if you revel with any other woman forcibly, your head then undoubtedly will break asunder into a hundred pieces."