In the name of Allah, the Gracious, the Merciful
The Prophet (ṣ) informed us that Muslims who recite Surat al-Kahf on Friday will receive a light from Allah for the upcoming week. The chapter does indeed contain many important lessons to reflect upon. What does ‘light’ mean in this tradition?
Abu Sa’id Al-Khudri reported: The Prophet, peace and blessings be upon him, said:
مَنْ قَرَأَ سُورَةَ الْكَهْفِ فِي يَوْمِ الْجُمُعَةِ أَضَاءَ لَهُ مِنَ النُّورِ مَا بَيْنَ الْجُمُعَتَيْنِ
Whoever recites Surat al-Kahf on Friday will have a light between this Friday and the next.
Source: al-Sunan al-Kubrá 5856, Grade: Sahih
The imagery of light is commonly used in the Quran as a synonym for guidance.
Allah said:
وَآتَيْنَاهُ الْإِنجِيلَ فِيهِ هُدًى وَنُورٌ
We gave him the Gospel, in which was guidance and light.
Surat al-Ma’idah 5:46
Hence, a Muslim who reads Surat al-Kahf on Friday, all things being equal, will receive more guidance throughout the week.
In an alternative wording of this tradition, the Prophet (ṣ) said:
مَنْ قَرَأَ سُورَةَ الْكَهْفِ كَمَا أُنْزِلَتْ كَانَتْ لَهُ نُورًا يَوْمَ الْقِيَامَةِ
Whoever reads Surat al-Kahf as it was revealed, there will be a light for him on the Day of Resurrection.
Source: al-Sunan al-Kubrá 5856
According to this narration, the good deed of the recitation of Surat al-Kahf will appear as light and guidance on the Day of Resurrection. This light will protect the Muslim from the horrors of the grave and the Hereafter.
This is similar to the narration of Abu Umamah (ra), in which the Prophet (ṣ) said:
اقْرَءُوا الزَّهْرَاوَيْنِ الْبَقَرَةَ وَسُورَةَ آلِ عِمْرَانَ فَإِنَّهُمَا تَأْتِيَانِ يَوْمَ الْقِيَامَةِ كَأَنَّهُمَا غَمَامَتَانِ أَوْ كَأَنَّهُمَا غَيَايَتَانِ أَوْ كَأَنَّهُمَا فِرْقَانِ مِنْ طَيْرٍ صَوَافَّ تُحَاجَّانِ عَنْ أَصْحَابِهِمَا
Recite the two illuminated chapters, Surat al-Baqarah and Ali Imran, for on the Day of Resurrection they will come as two clouds, or two shades, or two flocks of birds pleading for their companions.
Source: Ṣaḥīḥ Muslim 804, Grade: Sahih
Al-Nawawi commented on this tradition, writing:
سُمِّيَتَا الزَّهْرَاوَيْنِ لِنُورِهِمَا وَهِدَايَتِهِمَا وَعَظِيمِ أَجْرِهِمَا
They are called the “two bright ones” because of their light, their guidance, and their great reward.
Source: Sharḥ al-Nawawī ‘alá Ṣaḥīḥ Muslim 804
In sum, a Muslim who recites and reflects upon Surat al-Kahf each Friday will be rewarded for this act of worship, either with guidance in this life, or in the Hereafter, or both.
Success comes from Allah, and Allah knows best