At the time of writing these lines, the latest stable version of PHP is 5.6.10. Download the tarball via the following command:

[user@local ~]$ wget http://php.net/get/php-7.2.0.tar.gz/from/www.php.net/mirror

Once downloaded, extract the PHP archive with the tar command:

[user@local ~]$ tar xzf php-7.2.0.tar.gz