Does your employer have the legal right to keep hold of your passport?

I recently ended up my contract with my employer because of a medical grounds.

Actually, we don't have medical insurance, we are working 17 hours and I am not getting any assistance from the company.

After submitting my resignation letter, my employer accepted it but requested me to leave the country then only after he will proceed with the cancellation. He finally agreed after a long period of negotiation.

Now, the employment visa is cancelled and he forwarded me the residence cancellation where it's clearly mentioned that I have until 08 December grace period.

I asked him to give me back my passport which he is keeping it since I started working for the company and he refused, saying that only on the 19th Jan in reference to my flight date which is 20th of January.

In between, I received an offer with three times the salary I used to get and a lot of benefits including health insurance.

As per the labour law, does he have the right to keep hold of my passport even after cancellation of my employment visa?