In what book does Odysseus say, "Poseidon thinks he can stop me"?
I don't believe Odysseus ever utters this exact quote in the text of Homer's The Odyssey. You may be thinking of a similar quote that comes from the TV movie version of The Odyssey (1997) starring Armand Assante as Odysseus. In the film version, Odysseus speaks with Poseidon, who appears in the form of a turbulent wave in the sea he rules. When Poseidon chastizes Odysseus for not paying him the proper respect (and for blinding his son, Polyphemus), Odysseus responds,
"You cannot stop me!... No one, no one, will stop me from seeing Ithaca..."
In the 1955 movie Ulysses (starring Kirk Douglass), the hero tells Neptune (Poseidon): "There is no Neptune out there... I am here, undestroyed."
Perhaps the closest this quote comes in Homer's text is when Odysseus reveals to the Cyclops that "My name is No-man (Nobody)." Polyphemus later tells his brothers that "No-man is killing me..."