Miami Senior High School student Cristhian Reyes got a big surprise when someoe returned his lost wallet but there was one catch.

Instead of asking for money in exchange for the wallets return, the anonymous stranger gave Reyes $20 and added a note that read, in part: “I added $20 to it so you know the world is a great place. Do me a favor and when you get the chance, do something nice for someone else.”

Read more: ABC News