In book 23, what instructions does Penelope give to Eruycleia on page 461? How does this serve as a trick for Odysseus and what does Odysseus reaction prove?

Penelope maintains her neutral attitude toward Odysseus and asks Eurykleia to make up his bed outside her bedchamber. Odysseus is angry; no one can move the bed he made out of an olive tree. His intimate knowledge of the bed is proof that he is truly Odysseus, and Penelope embraces him and asks forgiveness for her suspicion.