noun
word of great value; each word worth a thousand pieces of gold
A yojijukugo meaning that a single word or character is extremely valuable, often used to praise excellent writing or a well-chosen expression.
彼の文章は一字千金の価値がある。
His writing is so excellent that every word is worth its weight in gold.
From the Chinese idiom 一字千金, literally 'one character, a thousand gold', originating from a story in the Records of the Grand Historian where Lü Buwei offered a thousand pieces of gold to anyone who could improve a single character in his work.