What chapter did Bruno not believe shmuel about not playing with boys in the book The Boy in the Striped Pajamas?

In "The Boy in the Striped Pajamas," Bruno expresses disbelief in Chapter 8 when Shmuel explains that he cannot play with the boys on the other side of the fence. Bruno struggles to understand the harsh realities of Shmuel's life and the concept of the rules separating them. His naivety leads him to question why Shmuel can't join him, reflecting his innocence and lack of awareness about the circumstances surrounding their friendship.