My employer is threatening me to send legal notice in case of incomepletion of projects.

I have served my notice period even one month extra after employer's oral confirmation about completion of work and projects. but after few days he is again claiming that work is not completed and telling me to come to office and finish the work. I asked that I have already completed all the work, I asked him about how much work is still pending, now he is saying about three to four months, this kind of trick he still did previously that's why this time I asked him to give me in return about my notice period. But now again he denied of giving me salary, he only gave salary up to second last month. Now whenever I ask him about salary and relieving letter, he threatens me to take legal action about demanding whole salary amount given during my employment alleging me for poor performance and non completion of projects. I have not signed any agreement for payment of this type of amount neither about the definition of projects completion. In my notice period letter, it is only written they can deduct amount in case of non completion of projects. Kindly suggest what should I do in this case.