眼 見 為 實 耳 聽 為 虛

眼見為實，耳聽為虛

眼见为实，耳听为虚

yan3 jian4 wei2 shi2 , er3 ting1 wei2 xu1

to believe what one sees, not what one hears (俗语 common saying). Don't believe what people tell you until you see if for yourself. It ain't necessarily so.