Brother In Prison Asking Me To Run Cash App For Him For His “store”

He says him and his cellmate buy extra product in the store when it’s open, and sells at double price during the week because “you would be surprised how much people want things right away”…. He wants me to create a Cashapp account and transfer money in and out of it to these random prisoners. They would “buy” whatever, a shirt or treats or something by having whoever they have on the outside send money to me. This sounds way wrong and illegal to me and I told him I’d do nothing that would get me in trouble and he assured me “it’s fine it’s fine, it’s all legit”… I told him I’d at least look into the legality of it so that’s why I’m here.

Edit: thanks all, gonna tell my brother no. Saddens me that he would even ask me to do anything like this, I never wanted it and now I’m afraid it’ll ruin our relationship. Also, I hope you all don’t downvote all posts asking questions or advice. Us normies don’t know anything and that’s why we come here.