玄沙示衆云：『諸方老宿，盡道接物利生，忽遇三種病人來，作麼生接？患盲者，拈鎚豎拂，他又不見；患聾者，語言三昧，他又不聞；患啞者，教伊說，又說不得。且作麼生接？若接此人不得，佛法無靈驗。』僧請益雲門，雲門云：『汝禮拜著！』僧禮拜起，雲門以拄杖挃，僧退後。門云：『汝不是患盲。』復喚近前來，僧近前，門云：『汝不是患聾。』門乃云：『還會麼？』僧云：『不會。』門云：『汝不是患啞。』僧於此有省。

Thomas Cleary renders the above into English as follows (with Yuanwuʼs 圜悟 annotations omitted here):

Xuansha said, "The adepts everywhere all speak of guiding and aiding people. Suppose they met with three kinds of invalids—how would they guide them? With blind people, they could pick up the gavel or raise the whisk, but they wouldn't see. Deaf people wouldn't hear what they said. Mute people could not be made to speak. How would they guide such people? If they couldn't guide these people, then Buddhism has no effect." A monk asked Yunmen for instruction on this. Yunmen said, "Bow." The monk bowed and rose. Yunmen poked at him with his staff; the monk drew back. Yunmen said, "You're not blind." Then Yunmen called him closer; when the monk approached, Yunmen said, "You're not deaf." Next Yunmen said, "Understand?" The monk said, "No." Yunmen said, "You're not mute." At this time the monk had an insight.

While the 'three sicknesses' here refer to blindness 盲, deafness 聾, and inability to speak 啞, this should not be understood as merely referring to physical impairment. Rather, the characters in the story represent people that have no understanding of 'real' seeing, hearing, or speaking, and the story asks us how we might lead such people to the truth. Cf. 三病 (which outlines other, non-related 'three sicknesses' ). 〔碧巖錄 T 2003.48.212c9〕 , 〔景德傳燈錄 T 2076.51.346b5〕 , 〔古尊宿語錄卷三十四〕 .

References:

Cleary, Thomas. 1998. The Blue Cliff Record. Berkeley:  Numata Center for Buddhist Translation and Research. 386–387.