Always consider your intellect to be lacking; otherwise too much faith in it surely leads to error.
Ali ibn Abi TalibIf you find that somebody is not grateful for all that you have done for him, then do not get disappointed because often you will find that someone else feels under your obligation though you have done nothing for him and thus your good deeds will be compensated, and Allah will reward you for your goodness.
Ali ibn Abi Talib