Resignation from job after working 12 YEARS

i m working as a doctor at private polyclinic since last 12 years .My sponsor has not given me any contact till now.But now he is telling me to sign a contract on the same salary what i am getting since last 7 years.In fact,when i joined the polyclinic,his father was my sponsor,but when his father died 3 years ago,he has take over the company and wants a contact with me.As the salary is the same,so i refused to sign the contact and i resigned from my job by giving 2 months notice.Now my contact is telling that i hv to finish ny contact,then i can go on exit.I am not able to understand that  my employer is talking about which type of what type of contract and what i have to do now?"

He's just trying to squeze you, tell him you'll go to the labor courts

Is this contract dated 12 years back when you joined? It seems he wants to legalize staff by making them sign employment contract dated backwards.
Legally speaking he cant make you serve the end of contract BUT if it is for short period of time there is no harm to complete the contract considering your lengthy period of employment and indemnity with them.

If you don't have any contract with your sponsor, then the law will consider the expiry date of your iqama as the last day of yours contract. Complete the the remaining time and give notice to your company of 60 days before expiry of iqama. Tell them you no longer interested to renew it. Read article 37,74, 76,77,80 and 81 of labor law too.