At-Tawbah 9:64

Yahtharu almunafiqoona antunazzala AAalayhim sooratun tunabbi-ohum bima feequloobihim quli istahzi-oo inna Allaha mukhrijun matahtharoon

The hypocrites are apprehensive lest a sūrah be revealed about them, informing them of what is in their hearts. Say, "Mock [as you wish]; indeed, Allāh will expose that which you fear."

The hypocrites are afraid that a Sūrah (a chapter of the Holy Qur’ān) may be sent down about them, which tells them what lies in their hearts. Say, “Go on mocking. Allah is surely to bring out what you are afraid of.”