A friend of mine just resigned from a company and they don't end up in a good relationship. So, he needs to make sure he gets all the documents now before he cancels his work permit. If he asks later, there's a possibility he won't get any document from them. These are documents he has asked so far. Is there anything else he needs to ask? Please, help!

1. Resignation agreement

2. Payroll slips

3. Work Certificate

4. BIS50 (Withholding tax certificate)