Nahjul Balagha Letter 66

To `Abdullah bin Abbas

And then, sometimes a person feels joyful about a thing which he was not to miss in any case and feels grieved for a thing which was not to come to him at all. Therefore, you should not regard the attainment of pleasure and the satisfaction of the desire for revenge as the best favour of this world, but it should be the putting off of the (flame of) wrong and the revival of right. Your pleasure should be for what (good acts) you have sent forward; your grief should be for what you are leaving behind; and your worry should be about what is to befall after death.