keep a civil tongue in one's head

To be polite in speaking.
He was very angry with his boss, but he kept a civil tongue in his head.
The bus driver began yelling at the woman and she told him to keep a civil tongue in his head.
Categories: polite tongue verb

An client error occurred: Error calling GET https://www.googleapis.com/youtube/v3/search?part=id%2Csnippet&q=%22keep+a+civil+tongue+in+one%27s+head%22&maxResults=4&videoEmbeddable=true&videoSyndicated=true&safeSearch=strict&type=video&key=AIzaSyCfLRuAZZNAQm6a5uDzgY-Tt668bxsppCs: (403) The request cannot be completed because you have exceeded your <a href="/youtube/v3/getting-started#quota">quota</a>.