During the Three Kingdoms period, the imperial advisor Guan Lu once visited the Minister of Personnel, He Yan, at his home, where another minister, Deng Yang, was also present. The three men chatted about everything under the sun, their spirits soaring.
Guan Lu was a master of the *Book of Changes*, and both He Yan and Deng Yang were eager to hear his insights. He Yan admitted he had nine questions about the *I Ching* that puzzled him, and Guan Lu answered each one clearly, earning He Yan's admiration for his vast knowledge. But Deng Yang challenged, "Everyone says Guan Lu understands the *I Ching* thoroughly, yet his words never touch on its actual phrases and meanings!" Guan Lu replied, "Those who truly grasp the *I Ching* do not discuss its literal words." He Yan found this response brilliant and praised Guan Lu's talk as "truly essential words without any tedious repetition."
The idiom "Yao Yan Bu Fan" means that what is said or written is concise and to the point, without being tedious or verbose—hitting the nail on the head in a single sentence.
Source: *Records of the Three Kingdoms*, "Biography of Guan Lu"
Meaning of the Idiom: Later, the Chinese idiom "要言不烦" came to describe what is said or written is concise and to the point, without being tedious or verbose—hitting the nail on the head in a single sentence.