The hypocrites are apprehensive lest a sūrah be revealed about them, informing them of1 what is in their hearts. Say, "Mock [as you wish]; indeed, Allāh will expose that which you fear."
The hypocrites are afraid that Allah will reveal a sūrah to His Messenger that will inform the believers about the disbelief that they conceal. Say, O Messenger: Continue, O hypocrites, mocking and poking fun. Allah will unveil what you are afraid of by revealing a sūrah or by informing His Messenger about the truth of your case.