know best
To have more knowledge and experience about something than anyone else. You should listen to her advice—after all, Mother knows best. As the person who designed the entire system, I think I know best about how to protect our users.
know ˈbest
know what should be done in a situation because you have knowledge and/or experience: ‘I want to get up.’ ‘But the doctor said you were to stay in bed, and he knows best.’Everyone said that I shouldn’t go there alone but I thought I knew best.