飲ㄧㄣˇyǐn流ㄌㄧㄡˊliú懷ㄏㄨㄞˊhuái源ㄩㄢˊyuán

喝水的時候，想到水的來源。語本北周·庾信〈徵調曲〉六首之六：「落其實者思其樹，飲其流者懷其源。」比喻不忘本。如：「受人恩惠當飲流懷源，知恩圖報。」也作「飲水知源」、「飲水思源」。

英lit. when you drink water, think of its source (idiom); gratitude for blessings and their well-spring, Don't forget where your happiness come from., Be grateful for all your blessings!