{And if you speak aloud, then indeed He knows the secret and what is even more hidden}. Qatada said: The secret is that which you speak to yourself, and that which is more hidden than it is that which is yet to come, which you have not spoken to yourself about.
﴿وَإِنْ تَجْهَرْ بِالْقَوْلِ فَإِنَّهُ يَعْلَمُ السِّرّ وأخفى﴾ قَالَ قَتَادَةُ: السِّرُّ: مَا حَدَّثْتَ بِهِ نَفْسَكَ، وَأَخْفَى مِنْهُ: مَا هُوَ كَائِن مِمَّا لم يحدث بِهِ نَفسك.