invoiceninja/app/Models/Credit.php

<?php
/**
 * Invoice Ninja (https://invoiceninja.com)
 *
 * @link https://github.com/invoiceninja/invoiceninja source repository
 *
 * @copyright Copyright (c) 2019. Invoice Ninja LLC (https://invoiceninja.com)
 *
 * @license https://opensource.org/licenses/AAL
 */

namespace App\Models;

use Illuminate\Database\Eloquent\Model;

class Credit extends BaseModel
{
    public function assigned_user()
    {
        return $this->belongsTo(User::class ,'assigned_user_id', 'id');
    }
}