Sze-ma Niu asked about perfect virtue.Go here to read the introductory post to this serialized version of the Analects of Confucius.
The Master said, "The man of perfect virtue is cautious and slow in his speech."
"Cautious and slow in his speech!" said Niu; "is this what is meant by perfect virtue?"
The Master said, "When a man feels the difficulty of doing, can he be other than cautious and slow in speaking?"
~ James Legge translation via The Internet Classics Archive ~