Is the employer letter mandatory for a spouse to file Family reunion long term visa? [closed]

Question

I am currently staying in Belgium on a Long term Type D visa and wish to bring my spouse here. My spouse is currently working in India. My query is whether the employer letter mandatory to file Family Reunion visa, as there is nothing mentioned in the Embassy of Belgium in New Delhi/Consulate General of Belgium site as well https://india.diplomatie.belgium.be/en/travel-to-belgium/visa/india