I don't understand what source Aditya referred to in order to answer a question regarding the brutal threat of dismissal solely based on taking 3-4 days of unexpected medical leave. Let the questioner not attach too much importance to the aforementioned answer, which was provided in good faith and with excessive enthusiasm.
Understanding Theory X Management Style
Ravindra, you may have heard of Theory X, as propounded by Douglas McGregor, which suggests that most people need to be coerced, controlled, and threatened with punishment in order to make them work. This is why many managers tend to be highly authoritative and sometimes insensitive, even towards sincere employees, when their behavior deviates from expectations and resort to using threats. Such a negative management style involves keeping employees in constant fear of punishment.
Therefore, do not be afraid. Instead, try to work smartly to capture his attention. When he is in a good mood, express your regrets for inadvertently triggering his anger due to your unexpected and unavoidable absence, and he will calm down.