The Day when secrets will be put on trial, (86:9)

Almuntakhab Fi Tafsir Alquran Alkarim

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

Tafseer Tafheem-ul-Quran by Syed Abu-al-A'la Maududi

(86:9) On the Day when man's deepest secrets shall be put to the test *5

The Day when secrets will be put on trial, meaning

*5) "The hidden secrets": the acts of every person which remained a secret to the world as well as those affairs which came before the world only in their apparent form, but the intentions, aims and secret motives working behind them remained hidden from the people. On the Resurrection Day aII this will be laid bare and not only will the acts and deeds of every person be examined but it will also be seen what was his motive and intention and object of so acting. Likewise, it also remained hidden from the world, even from the doer of the act himself, what effects and influences of his act appeared in the world, to what extent they spread and for how long they continued to work. This secret too will be revealed on the Resurrection Day and it will be fully examined as to what were the consequences of the seed that a person sowed in the world, what fruit it bore and for how long it affected the later generations for better or far worse.
 

The Day when secrets will be put on trial, meaning in Urdu

جس روز پوشیدہ اسرار کی جانچ پڑتال ہوگی