Daily Chinese Idiom Guessing Game
It is understood without being said; self-evident.
喻了解，明白。不用说话就能明白。形容道理很明显。
《孟子·尽心上》仁义礼智根于心，其生色也，然见于面。盎于背，施于四体，四体不言而喻。”
The respect between them was implicit and went without saying.