The sentences that are used to foreshadow Fortunato’s eventual fate is:
He raised it to his lips with a leer.
"I drink," he said, "to the buried that repose around us."
"A huge human foot d'or, in a field azure; the foot crushes a serpent rampant whose fangs are imbedded in the heel."
Foreshadowing is when the writer gives a hint on what would happen next in the story and in these sentences, the readers would think suspiciously of the man who is with Fortunato.