query about find and -exec

Hi,
i have query about "find" command. Do I need to put the command after -exec in single quotes? Why?

For ex. see output of these three find commands.

Any explanations?

cheers,
-Ashish

It is behaving exactly the was it should

Your first search returns ".", so you do "ls -lrt ." the string 'ls -l' is not a command and therefor does noting.

Thanks a lot Reborg. I was forgetting about the "."