A clear source lets another person check your understanding instead of borrowing your confidence.

Confidence is contagious, which is the problem with it. When you assert something without saying where it came from, people either accept it because of your manner or reject it for the same reason, and neither response involves thinking. A source hands them a way to check for themselves and turns your claim into something verifiable rather than something they must trust.

Say where you got it as you say the thing, including when the answer is a half-remembered article. Make it easy to look up. Being right matters less than leaving people able to find out for themselves.