zǐ zài chuān shàng yuē：“shì zhě rú sī fu，bù shě zhòu yè”
子在 川 上 曰：“逝 者 如 斯夫，不 舍 昼 夜”
Confucius says by the river，"time passes by just like the water in the river,goes on day and night,never stop and turn back."A metaphor means that things changes so fast,also indicating one should cherish time.
在......上：on,here means by the river.
者：person，here refers to people or things
夫：here used at the end to form an exclamation sentence.