A proverb meaning "Those who know do not speak; those who speak do not know." It implies that truly knowledgeable people are often quiet, while talkative people may lack real understanding.
会議で沈黙していた先輩に、知る者は言わず言う者は知らずという言葉を思い出した。
I remembered the saying "Those who know do not speak; those who speak do not know" when the senior stayed silent in the meeting.
彼は何も言わないが、行動を見ると本当に分かっていると分かる。まさに知る者は言わず言う者は知らずだ。
He says nothing, but by his actions you can tell he truly understands — exactly "those who know do not speak; those who speak do not know."