When iOS 11 goes live this fall users will be able to send money to their friends via iMessage, and spend the balance via a virtual Apple Pay card. The integration will also be able to do things like recognize when someone says “you owe me $10” and automatically prompt you to send them a payment.
Apple is integrating this peer-to-peer payments service with Apple Pay, which is what will make it a killer feature and eventually overtake Venmo and Square Cash payments. After someone sends you money, the balance lives on an Apple Pay virtual card stored in your Wallet app. While you can of course cash this money out to your bank account, you also can use the virtual card to pay anywhere Apple Pay is accepted, both in-store and online, without waiting a day for it to transfer to your bank account.
https://techcrunch.com/2017/06/05/you-can-now-send-your-friends-money-inside-imessage/