If they're holding your passport, how will you leave UAE? In my experience, employers request no liability letters from their departing employees' banks - you won't be able to give them one.

If you have left the UAE and absconded from your debts there - you would probably be able to enter Qatar. BUT if your flight to Doha is diverted to Dubai or Abu Dhabi(say for fog or flight problems) your goose could be cooked because they will check your details at UAE immigration and if a case has been filed against you by the bank or your employer - you'll be arrested and jailed.