hide your light under a bushel keep quiet about your talents or accomplishments.
☞ A bushel is a unit of measurement equal to eight gallons: in former times the word also referred to a container able to hold this amount. The expression has its source in Matthew 5:15: 'neither do men light a candle, and put it under a bushel, but on a candlestick'.
2013Daily Telegraph Never one to hide his light under a bushel, Mr Robertson afterwards declared, to loud guffaws from the press room: 'Who dares wins.'