Cassim is a character from the story "Ali Baba and the Forty Thieves," which is part of the collection known as One Thousand and One Nights. He is the older brother of Ali Baba, a poor woodcutter who discovers a secret cave filled with treasure. In the tale, Cassim is portrayed as greedy and ambitious. Unlike Ali Baba, who uses the treasure wisely, Cassim's desire for wealth leads him to seek out the cave for himself. His actions ultimately result in his downfall, highlighting themes of greed and the consequences of one's choices.