Terminated from company due to performance issue can demand for probation amount?

One of our employees is terminated form his services under his probation period and now he is demanding probation period amount from the company the probation period is mention in appointment letter.
Is there any rule for employment under which if any employee is terminated from company due to performance issue can demand for probation amount?
Please suggest

what is probation amount. Pl explain. During probation period the notice period is one day and hence is it one day salary is probation amount which you are mentioning.