كَالتَّهْدِيدِ، كَقَوْلِكَ لِعَبْدٍ لَا يَمْتَثِلُ أَمْرَكَ: لَا تَمْتَثِلْ أَمْرِي
For example, to a servant who disobeys, one says: do not obey me.
Here the prohibitive form serves threat, not an actual wish that the servant continue disobeying. The servant already disregards orders; the seemingly permissive “do not obey me” implies: persist, and you will face consequences.
This is a contextual rather than purely grammatical reading. Without the history of disobedience or threatening tone, the form could have a different force.