the sound of one hand clapping
A classic Zen kōan used in Rinzai Zen training. The phrase itself is a fixed expression and is not used in everyday conversation.
See also: 公案
"The sound of one hand clapping" is a famous Zen kōan.
公案 is the general term for a Zen kōan, while 隻手の音声 is a specific, well-known kōan.
The phrase originates from the Zen master Hakuin Ekaku (1686–1769) and is a well-known kōan. The literal meaning is 'the sound of one hand', where 隻手 means 'one hand' and 音声 means 'sound'.