Answer:
The two parts of the excerpt that show the White family does not believe in the talisman's power are:
"But I warn you of the consequences." "Sounds like the 'Arabian Nights,'" said Mrs. White, as she rose and began to set the supper.
And
"Don't you think you might wish for four pairs of hands for me." Her husband drew the talisman from his pocket, and all three burst into laughter as the Sergeant-Major, with a look of alarm on his face, caught him by the arm.
Explanation:
In the first part, instead of paying attention to what the sergeant was warning about the Monkey’s Paw, Mrs. White tells him that it sounded like one of the Arabian Nights, as if it was an invented story.
In the second part, the family began to joke about what they could ask for, while laughing without crediting anything Morris had said, even when he seemed totally alarmed by that situation.