Yarrow

There is a story about a witch from Yarrow. Each night a young boy was transformed into a horse when a local witch slipped a magical bridle over his head whilst he slept. She would ride the boy to her sabbat. One night the boy's older brother tricked the witch and managed to bridle her instead. She was transformed into a fine mare which the boy took on a long run before stopping at a blacksmiths to have his new horse shoed. The next morning the witch was found with horse shoes nailed to her hands and feet. I'm not sure who was the cruelest here.