1. Is there any requirement for overtime or standby in your work contract? If so, you may need to reply to the boss's information and return to work at the time required by the contract.
2. If your job doesn't explicitly require you to work overtime or stand by at any time, you can ignore the boss's information and reply to him when you go to work the next day, telling him that you saw his information after work, and generally don't accept this job during working hours.
If you think the boss's message is urgent or important, you can check the content of the message before replying to make sure that you fully understand his needs. When replying, you can simply answer. It is recommended to point out the current situation of yourself and your family and express your understanding and opinions.
If you are not sure what to do, you can ask your colleagues or other more experienced people, or consult the company's human resources department about relevant policies and procedures.
Finally, no matter what decision you make, you should ensure your safety and health, as well as your rest and family time.