It's wrong to betray the trust of family members.
Tom is mowing the grass like he promised his mother he would do when his friend Dan asks him to go to a movie.
Tom wants to go to the movie.
Tom tells Dan he can see the movie with him tomorrow and finishes mowing the grass.
Tom abandons mowing the grass and goes with Dan.
Tom's mother his happy that he successfully mowed the lawn.
Tom's mother is offended that Tom broke his promise to mow the grass.