To be precise in one's language

He was careful not to speak idle words. He was careful in the things he said. He was careful not to speak with an 'evil tongue'. He did not curse. He did not slander.

("Rav Yehuda said: The children of Judah who were careful about their language - their Torah was fulfilled in their hands, the children of Galilee who were not careful about their language - their Torah was not fulfilled in their hands" - Erubin 55 a"a, and so: "But the portion of our friends... they taught themselves the way to act that in the Land of Israel a person is obligated to speak Hebrew, and they were "They are careful about their tongues, lest a word that is not Hebrew be uttered from their mouths" - Agnon/ Tamol Shilshom, 135)

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