Answer:
In Chapter 9 of "The Kite Runner," Amir puts money and a wristwatch under Hassan's mattress as a way to frame him for theft. Amir does this because he is jealous of the attention that his father, Baba, gives to Hassan, who is Amir's Hazara servant and best friend. Amir hopes that his father, who is known for his strong sense of justice, will punish Hassan severely for the theft, which will diminish his father's affection for Hassan and increase his own standing in his father's eyes.
However, when Baba confronts Hassan about the theft, Hassan admits to it, but also says that he stole the items because he wanted to give them to Amir as a gift. Baba forgives Hassan, which surprises Amir, who expected his father to be angry and punish Hassan. Amir is left feeling guilty about his actions and the fact that his father still shows more affection towards Hassan than to him.
Amir's actions in framing Hassan for theft were motivated by his jealousy and desire for his father's attention and approval. However, his plan backfired, and he was left feeling guilty and ashamed for betraying his best friend.