Building a MVC Framework: Should I get an instance of Database, or should I extend with a "general" model class that already has an instance of DB

I am trying to get a database instance via any model-class that uses the database.

This is ideal in my opinion:

class UserAuthenticator 
{
    private $db;
    private $customer;

    public function __construct(Database $db, Customer $customer)
    {
        $this->db       = $db;
        $this->customer = $customer;
    }
}

Using a dependency injection.

But my team refuse to use dependency injections.

Which of the 2 options should be better and why?

Option 1: Just getting the instance of the database directly only in models that need the database.

class UserAuthenticator 
{
    private $db;
    private $customer;

    public function __construct()
    {
        $this->db       = Database::getInstance();
        $this->customer = Customer::getInstance();
    }
}

Option 2: Having a "general" Base class, that will extend all models, forcing them to use the database (which isn't a must in models right?)

namespace MyApp\Models\Base;
use MyApp\Core\Database as db;
class Database {

    protected $db;

    public function __construct() {
        $this->db = db::getInstance();
    }
}


use MyApp\Models\Base\Database as Base;
class UserAuthenticator extends Base
{
    private $customer;

    public function __construct()
    {
        parent::__construct();
        $this->customer = Customer::getInstance();
    }
}