en_tn/pro/16/10.md

Insightful decisions are on the lips of a king

Here the word "lips" is a metonym for what the king says. Alternate translation: "What a king says are insightful decisions" (See: rc://en/ta/man/translate/figs-metonymy)

his mouth should not betray justice

The word "mouth" represents the king himself. Alternate translation: "he should not speak deceitfully when he judges" (See: rc://en/ta/man/translate/figs-synecdoche)