Tafsir of At-Tariq 86:9

The Day when all the secrets will be examined. meaning, on the Day of Judgement the secrets will be tested. This means that they will be exposed and made manifest. Thus, the secret will be made open and that which is concealed will be well known. It is confirmed in the Two Sahihs on the authority of Ibn Umar that the Messenger of Allah said,

يرفع لكل غادر لواء عند استه يقال هذه غدرة فﻼن بن فﻼن

Every betrayer will have a flag raised for him behind his back, and it will be said, `This is the betrayal of so-and-so, the son of so-and-so.' Concerning Allah's statement,