.htaccess: How to create a redirect with spaces in the filename?

If a link was accidentally published with spaces, the user will not be able to open it. Here, a redirect from the incorrect domain can be useful.

Redirect 301 "/pfadmit leerzeichen.php" https://www.beispieldomain.de/pfadohneleerzeichen.php

Alternative, if the upper variant does not work on the server:

Redirect 301 /pfadmit[\s]leerzeichen.php http://www.beispieldomain.de/pfadohneleerzeichen.php