Returning a wallet minus the cash isn’t returning the wallet. It’s returning the part you didn’t want.

Half an honest act is not a smaller honest act. It is a theft with a friendly face on it, and the person getting their cards back is meant to be grateful enough not to count. What makes it tempting is the cover story, because technically you did hand it over, and technically is doing an enormous amount of work there.

If you ever end up holding something that belongs to someone else, pass it on without editing it. The test is whether you would be comfortable watching them open it in front of you. When the answer is no, you already know which part to put back.