PHP Passing an instance of a class to another class

I'm still kind of new to PHP OO programming techniques and I have a very simple broad question, is it generally bad practice to instantiate a class in a class then pass that instance to another class?

What I want is to be able to create an instance of a specific class I know I will always need through each user request. Class two is more than anything just a helper class, ideally in my application it would be a "loader" that loads the views.

First class which calls the other two classes:

require 'classTwo.php';
require 'classThree.php';

class first {
     public $classTwo, $classThree;

     public function __construct() {
          $this -> classTwo = new classTwo;
          $this -> classThree = new classThree;

          $this -> classThree -> displayNum( $this -> classTwo );

     }
}

Second class which is the helper class:

class classTwo {
     public function returnVal() {
          return 123;
     }
}

Third class is the action class where actual work and final display would happen:

class classThree {
     public function displayNum( $instance ) {
          echo $instance -> returnVal();
     }
}

Overall I just want to know if this is bad practice because I never seen it done before.

Thanks in advance!