This is an example of foreshadowing. Foreshadowing occurs in a narrative when an author gives the reader a hint of what is going to happen later in the story. In this case, the author tells us that the spell wanted to punish those who messed with their fate. It wanted to show them that "those who interfere with it do so to their sorrow." This foreshadows the fact that the next people to make a wish will also suffer dearly.
