Another idea: "Hear O Israel" The rabbis said: When Moshe went up to the heavens, he heard the ministering angels saying to the Holy Blessed One, "Blessed is the name of the glory of God's sovereignty for all time" and brought it down to Israel. And why doesn't Israel say it in public (aloud)? Rabbi Asi said: To what is it similar? To one who stole jewelry from the King's palace and gave it to his wife and said to her, "Don't adorn yourself with it in public, rather (wear it) in your house." However, on Yom Kippur when they are as clean as the ministering angels, they say it publicly, "Blessed is the name of the glory of God's sovereignty for all time."