What Does “Secret” Mean in Verse 6 of Sūrat al-Furqān?

“Secret” denotes, in its linguistic sense, something that is not manifest—anything hidden from the senses, the intellect, perception, time, and place.

In the blessed verse, this “secret” has a particular connection to the Qur’an. More of the Qur’an is hidden from creation than is manifest and apparent. The Qur’an is God’s secret; it is disclosed to us only to the extent that God wills.

َ عَنْ مُحَمَّدِ بْنِ مُسْلِمٍ قَالَ: سَأَلْتُ أَبَا عَبْدِ اللَّهِ ع عَنْ قَوْلِ اللَّهِ عَزَّ وَ جَلَّ- يَعْلَمُ السِّرَّ وَ أَخْفى‏
قَالَ السِّرُّ مَا كَتَمْتَهُ فِي نَفْسِكَ وَ أَخْفَى مَا خَطَرَ بِبَالِكَ ثُمَّ أُنْسِيتَهُ.
Maʿānī al-Akhbār, text, p. 142

Muḥammad ibn Muslim relates: I asked Imam al-Ṣādiq, peace be upon him, about the words of God عزّ و جلّ: يَعْلَمُ السِّرَّ وَ أَخْفى‏
(He knows what is secret and what is even more hidden in the world—Ṭā Hā 20:7). He replied: “‘Secret’ is what you deliberately conceal within yourself; ‘what is even more hidden’ is something that was once in your memory, but that you later forgot.”