In book 11 of the Odyssey, Teiresias cautions Odysseus about the negative consequences of his past and future actions. The prophet warns Odysseus specifically about Poseidon’s revenge for the blinding of Kyklops and the dire ramifications if his men touch any animal in Helios’s herds.

Before arriving in the Land of the Dead, Odysseus and his crew already endured many challenges. In book 9, he and many of his men escape from the cave of Kyklops, the one-eyed son of Poseidon, by stabbing the giant’s eye and stealing his sheep. Unbeknownst to Odysseus, Kyklops pleaded to his father for vengeance:

O hear me, lord, blue girdler of the islands,
if I am thine indeed, and thou art father:
grant that Odysseus, raider of cities, never
see his home
(book 9, 552–5, Fitzgerald translation).

Teiresias understands that Odysseus wishes to journey home to Ithaka but warns that

anguish lies ahead;
the god who thunders on the land prepares it,
not to be shaken from your track, implacable,
in rancor for the son whose eye you blinded.
One narrow strait may take you through his blows:
(book 11, 110–112, Fitzgerald translation).

This passage foreshadows harrowing obstacles in the next book. In book 12, Odysseus and his crew must navigate their ship through a “narrow strait” flanked by the sea monster Skylla and the monstrous whirlpool Kharybdbis. Although forewarned, Odysseus ultimately loses six men to Skylla.

The prophet also offers Odysseus proactive advice: as tempting as it may be, do NOT touch the livestock at the next land of Thrinákia where

you’ll find the grazing herds of Hêlios
by whom all things are seen, all speech is known.
Avoid those kine, hold fast to your intent,
and hard seafaring brings you all to Ithaka.
But if you raid the beeves, I see destruction
for ship and crew.
(book 11, 116–121, Fitzgerald translation).

Despite admonishing his men to NOT raid the sheep, Odysseus is dismayed when his hungry men rebel and kill the flock for food. An enraged Hêlios asks Zeus to punish Odysseus and his men, who are then hit with yet another storm. As Teiresias predicts, Odysseus loses the rest of his crew and ends up stranded on Calypso’s island for seven years:

Though you survive alone,
bereft of all companions, lost for years,
(book 11, 121–122, Fitzgerald translation).

Finally, the prophet warns Odysseus of what he will find when he ultimately reaches his house in Ithaka:

under strange sail shall you come home, to find
your own house filled with trouble: insolent men
eating your livestock as they court your lady.
Aye, you shall make those men atone in blood!
(book 11, 123–126, Fitzgerald translation).

Odysseus has no idea of what Penelope has been enduring during his absence, so Teiresias provides a window on the chaotic scene. Most importantly, the prophet’s warning includes advice to Odysseus to kill the men and make amends. Homer foreshadows the bloodbath of Odysseus’s homecoming.

In book 10, Odysseus requests to leave Circe's island, and the goddess instructs him to visit Hades and Persephone's home to consult the deceased Theban prophet Teiresias before heading back to Ithaca. Circe tells Odysseus that Teiresias will give him necessary information regarding his journey home, and Odysseus and his crew obey her commands by sailing across Oceanus to the dreaded underworld. In book 11, Odysseus and his crew journey to the boundaries of Oceanus, where they make sacrifices and pray to the families of the dead.

Several terrifying shades appear out of a hole, and Odysseus speaks to the shade of their deceased companion, Elpenor, before consulting Teiresias's shade. The shade of Teiresias informs Odysseus that Poseidon is still upset with him for blinding his son and will make his journey extremely difficult. However, Teiresias assures Odysseus that he will eventually return to Ithaca.

The shade of Teiresias proceeds to warn Odysseus to leave Helios's cattle alone and unharmed when his crew reaches the island of Thrinacia. If Odysseus and his men harm any of Helios's cattle, the crew will be destroyed, and Odysseus will return home on someone else's ship. Teiresias then tells Odysseus that numerous suitors have ravaged his home, and he will need to get revenge on them when he returns to Ithaca.

In Book Eleven, Odysseus descends into the Underworld, where he meets with Tiresias, the legendary prophet. Tiresias warns him that, regardless of Odysseus's wishes, he has Poseidon set against him, something which he must contend with. Even so, Tireasias does tell Odysseus that "you and your crew may still reach home, / suffering all the way, if you only have the power / to curb their wild desire and curb your own." (The Odyssey, trans. Robert Fagles, Penguin Classics Edition, New York: 1996, paperback edition, pp. 252-3). In other words, while they can return home, should they gain mastery over themselves, there will always be hardship on the path ahead of them.

In particular, Tiresias warns Odysseus about the cattle of Helios, who graze on the island of Thrinicia. Tiresias warns that should the cattle come to harm, Odysseus's ship and crew would be destroyed, and even should Odysseus survive the destruction, he would "come home late / and come a broken man." (253). Here Tiresias predicts events as they will proceed: should the cattle be harmed, Odysseus will find his return delayed, and when once he finally does return home, it would be to find his house in disarray, with suitors preying upon it, seeking marriage with his wife.

In The Odyssey Odysseus is warned by the blind prophet Tiresias that all of the sacred cattle of the Sun God Helios should be left alone. Tiresias says that the cattle should be avoided at whatever cost, and that if they are not, the men will all meet their doom.

He also tells Odysseus that when he returns home he will find suitors eating his food and courting his wife. He is told that he must send these men away or kill them. 

Lastly, he was told that he should find a place so far inland that the inhabitants ate unsalted meat and wouldn't know of the sea or be able to recognize an oar. Specifically he said Odysseus should walk until someone asked him about his oar and called it a "winnowing fan" rather than an oar (because they didn't know what an oar was, presumably). In that spot Odysseus is to stick the oar in the ground and make a sacrifice to Poseidon so that he can continue on his journey home safely. 

Odysseus intends to follow all of the prophet's instructions. He leaves to pray and in his absence tells his men to leave the cattle untouched. Unfortunately, food runs scarce and his men get hungry. Since they are temporarily trapped on the island, the men decide to fill their stomachs the only way they can think of: by killing and eating the sacred cattle. Helios is furious about this transgression, and he convinces Zeus to punish the men. On the trip home the ship wrecks and only Odysseus, who did not eat the sacred cattle, survives.