Carved on a stone刻在石头上

两个朋友结伴穿越沙漠，旅途中二人突然吵了起来，其中一个掴了对方一记耳光。被打的人感到自己受了伤害，但什么也没有说，只是在沙地上写下了这样一句话：“今天我最好的朋友掴了我耳光。他们继续前行，看见到处绿洲，他们正打算在那里洗澡时，刚才被打的人不小心陷入了泥潭，开始深陷，他的朋友救了他。
等他从几近淹死的边缘苏醒过来后，他在石头上刻下：“今天我最好的朋友救了我的命。”他的朋友问：“为什么我伤你之后，你在沙子上写字，现在却把字刻在石头上?” 他回答道：“当有人伤害了我们，我们应该把它写进沙里，宽恕的风会把仇恨抹去。而当有人为我们做了好事，我们应当把它刻在石头上，没有风可以将它抹去。”
The story goes that two friends were walking through the desert. During some point of the journey they had an argument， and one friend slapped the other one in the face.
The one who got slapped felt hurt， but without saying anything， wrote in the sand： "Today my best friend slapped me in the face."
They kept on walking until they found an oasis， where they decided to take a bath. The one who had been slapped got stuck in the mire and started drowning， but the friend saved him.
After he recovered from the near drowning， he wrote on a stone： "Today my best friend saved my life."
The friend who had slapped and saved his best friend asked him， "After I hurt you， you wrote in the sand and now you write on a stone. Why?"
The other friend replied： "When someone hurts us we should write it down in sand where winds of forgiveness can erase it away. But when someone does something good for us， we must engrave it in stone where no wind can ever erase it."