While most landlords here in Doha are no doubt terrible people to deal with, you may get away by giving him a 2-month notice period in WRITING. Send this notice to him through email if possible. This gives you some ground to stand on. Further, if he fails to return your cheques even then, lodge a complaint with Rental Dispute Settlement Committee and see if they can help you out. Their office is located in the vicinity of Holiday Villa on the C-Ring road. If nothing works out, then go with "obeying" the Landlords wishes as that would be best for you. I believe he can create problems for you at the time of your exit as he is holding your cheques. Don't take him to court as it requires months to get a verdict.