Custom validation and error message in Laravel 5

PasswordController.php

<?php

namespace App\Http\Controllers\Auth;

use App\Http\Controllers\Controller;
use Illuminate\Foundation\Auth\ResetsPasswords;

class PasswordController extends Controller
{
    /*
    |--------------------------------------------------------------------------
    | Password Reset Controller
    |--------------------------------------------------------------------------
    |
    | This controller is responsible for handling password reset requests
    | and uses a simple trait to include this behavior. You're free to
    | explore this trait and override any methods you wish to tweak.
    |
    */

    use ResetsPasswords;

    protected $redirectTo = '/dashboard';

    /**
     * Create a new password controller instance.
     *
     * @return void
     */
    public function __construct()
    {
        $this->middleware('guest');
    }

    /**
     * Get the password reset validation rules.
     *
     * @return array
     */
    protected function getResetValidationRules()
    {
        return [
            'token' => 'required',
            'email' => 'required|email',
            'password' => 'required|confirmed|min:8|regex:/^(?=.*[a-z])(?=.*[A-Z])(?=.*\d)(?=.*[^a-zA-Z0-9]).+$/',
        ];
    }

    /**
     * Get the password reset validation messages.
     *
     * @return array
     */
    protected function getResetValidationMessages()
    {
        return [
          'password.regex' => 'Password must contain at least 1 lower-case and capital letter, a number and symbol.'
        ];
    }
}