`Abdullah ibn al-'Abbas used to say, "Apart from the Prophet's sayings I did not derive greater benefit from any saying than this one."
Let it be known to you that sometimes a man gets pleased at securing a thing which he was not going to miss at all and gets displeased at missing a thing which he would not in any case get. Your pleasure should be about what you secure in respect of your next life and your grief should be for what you miss in respect thereof. Do not be much pleased on what you secure from this world, nor get extremely grieved over what you miss out of it. Your worry should be about what is to come after death.