Foreshadowing points to an upcoming event in the story. Shakespeare used the literarcy technique in many of his plays. The following lines can be used as evidence:
RICHARD III (Duke of Gloucester): Go, tread the path that thou shalt ne'er return.
Simple, plain Clarence! I do love thee so,
That I will shortly send thy soul to heaven,
If heaven will take the present at our hands.
But who comes here? the new-deliver'd Hastings?
The lines show that Richard is going to kill Clarence. While he was thinking about it, Hastings enters the room. Shakespeare's usage of foreshadowing comes to light at this point that there is going to be something between Richard and Clarence.