Htaccess redirect wiout trailing slash is working but with it is not

I have a WordPress website. And I want to redirect a URL to another 3rd party domain. The issue is that destination domain cannot have trailing slash.

So I want to redirect http://www.domain.com/xyzxyzxyz to http://3rd-party-domain.com/?something

It’s working fine for without trailing slash request urls

http://www.domain.com/xyzxyzxyz -> http://3rd-party-domain.com/?something

but when I try http://www.domain.com/xyzxyzxyz/ then it does not work because it adds trailing slash in destination URL too, which gives error.

I have tried these rewrite rules

Redirect 301 /xyzxyzxyz http://3rd-party-domain.com/?something
Redirect 301 /xyzxyzxyz/ http://3rd-party-domain.com/?something

Not working 🙁

Please let me know how to fix this.