Final exit issue with employer

My husband has been working as marketing manager in a construction company in saudi arabia from past 6 years. He resigned in october 2017 giving a two months notice period. The company accepted his resignation but with immediate acceptance one month notice pay.
They cleared all the dues and issued a final exit on tuesday 14th november 2017.We asked them to book our flights for november 16, 2017 But on november 15 the company cancelled our exit visas. When my husband asked the company hr people, they said he has to sign the paper saying that he will not come back to saudi.
My husband refused to  sign it. Now they are threatening him to sign it. My husband went to labour court now. He will have the hearing next week.
The company people called again and made lots of threats that you have to sign the paper in either case or they will ban him from entering saudi or will send him to police.
He has no criminal offence. And has good employment record. Can the labour court force him to sign that paper? Can the labour court ban him?

Please note that the company paid the gratuity and even had issued the final exit.
Thanks