pre_comment_on_post action-hook . WP 2.8.0

Fires before a comment is posted.

Usage

add_action( 'pre_comment_on_post', 'action_function_name_7403' );
function action_function_name_7403( $comment_post_ID ){
	// action...
}

$comment_post_ID(int)

Post ID.

Where the hook is called

do_action( 'pre_comment_on_post', $comment_post_ID );

Where the hook is used (in WP core)