As pointed out by Ashutosh, the Terms & Conditions of the Appointment are important. During the Probation Period, which is 3 to 6 months in most companies, the company reserves the right to terminate without specifying a reason. Moreover, if the appointment states that the position is purely temporary and a specific period is mentioned in the Appointment Letter, then there is no legal or moral choice but to exit. For example, if you are appointed to cover a position due to Maternity Leave, then the post is evidently temporary.
In other words, the position to which you are appointed should not be of a casual/temporary nature, and you should have served for a minimum of 120 days (6 months) for the Labor Commissioner to be convinced that the position was not temporary. On the contrary, if the position is permanent, but you have worked less than the minimum 120 days, you still risk losing it. My explanation above should clarify where you stand.
Regards, - Abdul Quadir