By nature, the child expects that promises will be kept. When the parents fulfill their small promises the child gets trained in this important aspect of life. But if people take their small promises lightly and neglect them, the child takes the negative example and develops the habit of breaking his word. Children start believing that promises are made to be broken.
If the parents make false promises to momentarily calm the child, they are inadvertently training the child to make false promises. Do the parents ever imagine what impact they are making on the impressionable minds of the children? In fact; children automatically emulate the actions and words of their parents.
A selection from Principles of Upbringing Children by Ibrahim Amini