It's discouraged from causing hardship to others.
Alex can get a better job at his company if he tells his boss that his colleague made a mistake and lost a major client.
Alex has to decide whether to ruin his colleague's chances for promotion.
Alex doubles his efforts at work, improving his own performance, but he doesn't say anything about the shortcomings of his colleague.
Alex meets with his boss and tells him that it was his colleague's mistake that cost the company a large client.
His boss recognizes his strengths and his effort, and also understands his colleague's weaknesses, so Alex gets a promotion without sacrificing his social standing at work.
His colleague is fired and none of his other colleagues trust him anymore, leaving Alex isolated at work.