The simple hand shake, the verbal agreement, the moral obligation of a promise is a way of progressing ideas.
We make promises everyday. When we purchase an item, we promise to pay. When we make a commitment we are making a promise.
It is very sad when people fail to keep their promise. In cases of restaurants who take bookings on a busy night and the patron fail to keep their reservation – this is a broken promise.
Promises, however they are dealt, is a moral obligation of verbal agreement so therefore respecting a promise is a show of good character.