As a youth, Liang, Duke Ma, the Junior Guardian was once reading a book beneath a lamp and close to a window, when suddenly a great hand like a door leaf pushed through the lattice into the window. The next night it came again, but the gentleman moistened his writing brush in orpiment water, and wrote his signature in large script. From outside the window came a loud call: “Wash it off for me quickly, then you won’t come to harm.” The gentleman paid no attention but went to bed. Before long it had become very angry, seeking with ever more urgency to wash it away, but the gentleman paid no attention. Just before dawn, it made plaintive wails and was quite unable to withdraw its hand, saying: “The gentleman will be a great noble, I was just testing the gentleman; how can the gentleman bear my extremity? Can the gentleman alone be unaware of the affair of Wen Jiao and the rhino horn?” The gentleman then came to a sudden realisation, washing away his signature with water, and the hand then shrank and withdrew; he looked but there was nothing to see.
Anon, Huhai xinwen yijian xuzhi, 後2.237 (Tale 427):
 The biography of Ma Liang 馬亮, courtesy name Shuming 叔明, is found at Songshi 298.9915-17. The Huhai account is considerably abbreviated compared to a previous (Song-era) telling. Compare Zhang Shizheng 張師正, Kuoyizhi 括異志 (Inclusive Reports on Strange Matters) (Project Gutenberg version):
Junior Guardian Ma 馬少保
The Junior Guardian of the Heir Apparent Duke Ma Liang himself related that in his youth he studied at a Buddhist monastery outside the walls of Luzhou. One night, when reading beneath a lamp close to a window, there was a huge hand like a door leaf that extended before him, as if on a great rope. The gentleman did not look at it, but continued to peruse his books as before. The same happened night after night. The gentleman thus told people, and a Daoist priest said: “I have often heard that spirirs fear red orpiment; you should try to get rid of it with that.” He thus ground red orpiment and soaked it in water, then secretly placed it close by on a table. That evening, when the huge hand arrived again, the gentleman used a brush moistened in red orpiment and wrote on it the single large character cao (‘grass’). When he had finished writing, a great yell came from outside the window: “Wash it off quickly, if not, misfortune will reach you!” The gentleman carried on as before, not listening, and then, leaving the lamp, went to bed. Before long it became extremely angry, and demanded all the more urgently that it be washed off; the gentleman did not respond. As dawn arrived, its cries became ever more plaintive, but it could not withdraw, so spoke again: “The gentleman will be greatly distinguished; I won’t scare other people; I only wanted to joke, but offended the gentleman; how can you stand to see me so extremely terrified? I have certainly caused offence, but, if the conditions of the nether world are revealed to the world through the gentleman’s action that will not be to the gentleman’s profit. Is the gentleman alone unaware of Wen Jiao’s burning the rhino horn to light cow island?” The gentleman, coming to a sudden realisation, then washed off the ‘grass’ character with water, and warned the creature not to return and bother people in future; the monster yielded gratefully and departed. The Jinshi scholar Wei Tai reported that Duke Ma had often spoken of this to his grandfather.
http://www.gutenberg.org/files/27092/27092-0.txt (accessed 21/01/18)
 This refers to the account in the Jinshu 晉書 biography for Wen Jiao 溫嶠 (288-329 CE, courtesy name Taizhen 泰真), which relates his death to his exposure of water spirits by illuminating them with a burning rhino horn, and a subsequent warning about such behaviour in a dream. The biography is found at Jinshu 67.1785-96, and the incident at 67.1795.
Yuan Haowen 元好問, Chang Zhenguo 常振國 (ed), Xu Yijian zhi 續夷堅志 (Continued Records of the Listener), and Anon., Jin Xin 金心 (ed.), Huhai xinwen yijian xuzhi 湖海新聞夷堅續志 (Continuation of Records of the Listener with New Items from the Lakes and Seas) (Beijing: Zhonghua shuju, 1986).