If you sent Monero (XMR) using Coin Wallet v6.24.0 or later, you can prove the payment to the recipient.
1. Open "History" tab and click on your outgoing transaction.
2. Copy Recipient, Transaction key and Transaction ID.
3. Open a Monero explorer that supports payment proof:
- https://localmonero.co/blocks
- https://xmrchain.net
- https://blockchair.com/monero
- https://monerohash.com/explorer
4. Search for your transaction using Transaction ID from Step 2. Enter the Recipient and Transaction key from Step 2 and click "Prove payment" button..
5. You will see a confirmation of the XMR amount and recipient address.
Also, you can verify your payment via Monero GUI Wallet (full guide) by using Recipient, Transaction key and Transaction ID from Step 2.