Should I validate user input inside or outside of the User object when creating a new account?

Question

When making an account system I have two objects, User & Validator, and I am wondering if it is better to validate the user input outside of the User class or inside the class? For example, should it be:
In signup.php:
$passwordAuth = new Validator($password);
$usernameAuth = new Validator($username);
$user = new User;
If ($usernameAuth->verify() && $passwordAuth->verify()) {
$user->username = $username;
$user->password = $password;
$user->create();
}
Or just take the above validation code and make it apart of the User create function. Then all that would be in signuo.php class is:
$user = new User;
$user->username = $username;
$user->password = $password;
$user->create();

Answer 1

It's user input so it should probably be inside the User class.