"on the Day when the secrets will be made known,"
Sayyed Abbas Sadr-Ameli
On the Day when hidden things will he made manifest
Al-muntakhab fi tafsir al-Qur'an al-Karim
That is on the Day of Resurrection, when secrets are brought into the open and man’s countenance will reveal, against his will, all he had hoped would be kept secret and will betray him to his fall or to his exultation