how can I check my rsa passphrase?

Use:

ssh-keygen -y

-y      This option will read a private OpenSSH format file and
        print an OpenSSH public key to stdout.

Example:

$ ssh-keygen -y -f ~/.ssh/id_rsa_file

This will prompt to enter the passphrase. Given a wrong passphrase it will say "load failed" otherwise it will print the OpenSSH public key to stdout.

Try ssh-keygen -p:

-p      Requests changing the passphrase of a private key file instead of
        creating a new private key.  The program will prompt for the file
        containing the private key, for the old passphrase, and twice for
        the new passphrase.