Sadhu for further going into. Not sure if the question is right understood, Nyom. Maybe Nyom could bring up a sample. It's very importand part of right speech and one can see the impact and relation to trade very clear. For Sila is the reason of wealth and people who act like they say are always seen as successful, while insuccessful are those who tend to speak and promise much but fail then or forget.
Hardly ever "unlucky" change their tendencies and of course it looks strange if reminding another as receiver.
It's surely worthy to give a talk on it, althought many will possible believe that one speaks in own interest. A very related topic "changing one mind" is here discussed. It's not always a fault if changing one mind, quite a contract, especially if it's fullfilling would require doing wrong, or if striving after higher instead. Remember the flower seller who had a contract with the king but on the way offered the flowers to the Buddha instead.
Is changing your mind same as lying? Breaking promises As it is a part of wrong speech, done often toward people of goodness here, Atma tries to give a talk in Khmer later as well.