In book 23 explain what the prophet Tiresias told Odysseus that he must do now. Give a quote to support your answer

He has one more trial, however, that Teiresias told him about: he must take an oar through the mainland and find men who do not know of the sea, until one asks what the oar is. Then he shall plant the oar there and make a sacrifice to Poseidon, return home, and make further sacrifices to all the gods. In bed, she tells him about the suitors, and he recounts his adventures.