The man in charge must concern himself with details. If he does not consider them important, neither will his subordinates. – Hyman Rickover

Hyman Rickover was a U.S. Navy admiral who served during World War II who is known as the “Father of the Nuclear Navy” for his role in developing the first nuclear-powered submarine.

Back to the quote:

The man in charge must concern himself with details. If he does not consider them important, neither will his subordinates.

Hyman Rickover

This quote has both a leadership and business lesson. Hyman was not in the business sector and i doubt he had much business leadership or entrepreneurship experience, but due to his position in the military sector, he was did have a leadership experience.

This quote has much more meaning and truth than Hyman himself would have expected.

The first half: The man in charge must concern himself with details.
Pretty straight forward, the leader or manger or CEO / business owner , should be interested in details. That does not mean that he should take care of them, but simply focus on them. Some would argue this is micromanagement, in reality it is not, it is setting a high standard.

The second half: If he does not consider them important, neither will his subordinates.
This is another truth, if the employees sees a low bar, they will not try to raise the bar. In the majority of cases, employees try to do the bare minimum, that is why you should give them an idea of what you see as important.
Another point, maybe not directly intended, achieving 90-97% efficiency in a domain requires few years, it is the last 2-3% that require decades of experience, thus a more skilled leader has a role in perfectly finishing the task.