Returning null Value for User from Model

I'm getting a null value for the user at http://localhost:8000/messages. I am trying to get the user table values within the Message model. It also gives a null value in the console.

Route

Route::get('/messages', function () {
    return App\Message::with('user')-> get();
})-> middleware('auth');

Model

<?php

namespace App;

use Illuminate\Database\Eloquent\Model;

class Message extends Model
{
    protected $fillable = ['message'];

    public function user()
    {
        return $this->belongsTo(User::class);
    }
}

User Model code:

<?php

namespace App;

use Illuminate\Notifications\Notifiable;
use Illuminate\Foundation\Auth\User as Authenticatable;

class User extends Authenticatable
{
    use Notifiable;

    /**
     * The attributes that are mass assignable.
     *
     * @var array
     */
    protected $fillable = [
        'name', 'email', 'password',
    ];

    /**
     * The attributes that should be hidden for arrays.
     *
     * @var array
     */
    protected $hidden = [
        'password', 'remember_token',
    ];

    public function messages()
    {
         return $this-> hasMany(Message::class);
    }
}

Snapshot