The saying you're referring to is: "Empty vessels make the most noise." This proverbial expression suggests that people who constantly boast or feel the need to proclaim their intelligence, abilities, or knowledge are often lacking in substance and actual accomplishments. In contrast, truly knowledgeable and intelligent individuals tend to let their actions and achievements speak for themselves rather than seeking validation through self-praise. The saying emphasizes the idea that genuine intelligence and wisdom are better demonstrated through actions and deeds rather than through mere words or self-promotion.