Possible solution to unix error "X11 connection rejected because of wrong authentication"

I was trying to start an X window Application on my server as user Oracle, but received the error

oracle@myserver:[testdb01]# xclock
X11 connection rejected because of wrong authentication.
Error: Can't open display: localhost:10.0

The DISPLAY variable was set to localhost:10.0.

The solution was to logon as root and execute

root@myserver~]# xauth list $DISPLAY

The result from this was

myserver.mydomain.com/unix:10  MIT-MAGIC-COOKIE-1  83f9f76d03106db6fc0880edfb005607

Then change user back to oracle and add the cookie to oracle's authorization file:

[root@myserver ~]# su - oracle
oracle@myserver:[testdb01]# xauth add :10 MIT-MAGIC-COOKIE-1 83f9f76d03106db6fc0880edfb005607

If you get the error:

xauth:  file /home/oracle/.Xauthority does not exist

create the file first:

touch /home/oracle/.Xauthority

Then retry the "xauth add" command above.
Verify with:

oracle@myserver:[testdb01]# xauth list $DISPLAY
myserver.mydomain.com/unix:10  MIT-MAGIC-COOKIE-1  83f9f76d03106db6fc0880edfb005607
oracle@myserver:[testdb01]# echo $DISPLAY
localhost:10.0

I could now execute X Applications:

oracle@myserver:[testdb01]# xclock