NOC for Expats who came from NOC

Friends I need your legal advice for some who are aware of the Qatar Labor Law. My husband came from NOC and transfer from his previous company before now that he resigned from his current company, it refused to give him NOC. Isn't that they don't have any right to hold back or deprive him of his NOC since from the beginning they recruited him from NOC? The visa that my husband consumed does not belong them but neither only sponsored by them. Please if someone can advice, help or suggest on how can we run after the company to return back his NOC.