There is a story in the diary of a certain court noble that while drinking with Masamoto and Karahashi in the evening, Kosen told them that 'I can't talk about the secrets of the method with words' and wrote '張良化現大天魔源義経神' on tanzaku (a long, narrow card on which Japanese poems are usually written vertically), and the monks fled out of fear.
夜も更けた頃、興仙・政元・唐橋らが酒を飲んで語るうち、興仙は「法の奥義は、言葉では表せない」と短冊に「張良化現大天魔源義経神」と書いて見せたので、僧侶たちは怖がって逃げた、という話が、公家の日記に残っている。