The Prophet Muhammad (peace be upon him) said:
Read the Quran, for it will come as an intercessor for its reciters on the Day of Resurrection. (Muslim)
Know that there are external manners and internal hidden secrets to reading the Quran.
As for the hidden secrets, they are five:
1- Sense the Greatness of the Words
That you sense, at the beginning of your reading, the greatness of the words by sensing the greatness of the speaker.
You do this by feeling in your heart the presence of The Throne and His Dominion, the heavens and the earth, and all that is in between them of Jinn, humans, animals and plants; and that you remember that the Creator of all of them is One, and that they are all within His Grasp and Power, experiencing His Favors and Compassion; you feel that you want to read His words and see through them His Attributes, His Beauty, His Knowledge and His Wisdom.
Know that just as the Quran can only be touched by those who have purified themselves—while being veiled from the rest—its true meaning and secrets are also veiled from the hearts if they are vile and impure.
2- Contemplate the Quran
That you contemplate its meanings while reading, if you [want to be] of the people of the Quran. Repeat all that your tongue has recited unmindfully; don’t count mindless reading as part of your good deeds because the purpose of beautiful recitation is to increase contemplation.
Ali (may Allah be pleased with him) said:
“There is no goodness in an act of worship that is void of understanding, nor in recitation that lacks contemplation.”
3- Reap the Fruits of Knowledge
That you reap the fruits of knowledge from their branches and seek them from their abodes, as you contemplate; don’t seek the antidote from where you seek the gems, nor the gems from where you see the musk and [fragrance], for every fruit has its own branch and every gem its own source.
This is facilitated by knowing the ten categories we have sorted the Quran into. Of these ten, are the following:
1- That of the Quran which relates to Allah (Glory be to Him), His Attributes and Actions; seek from it the knowledge of greatness and magnificence.
2- That which relates to guidance to the Straight Path; seek from it knowledge of mercy, compassion and wisdom.
3- That which relates to the destruction of enemies; seek from it knowledge of honor and might, conquest and overpowerment.
4- That which relates to the lives of the prophets; seek from it knowledge of kindness and blessings, favors and generosity.
So, for each category, seek from it that which is most befitting…
4- Avoid What Prevents You from Understanding
That you avoid whatever inhibits your understanding, because that is the covering that prevents you from understanding. Allah (glory be to Him) says:
…Indeed, We have placed over their hearts coverings, lest they understand it, and in their ears deafness… (18:54)
The God-conscious seeker of truth is tested with one of two kinds of coverings: either the veils of doubt and denial that test those who are weak in faith, or the veils of heart-saturating desires that test the ones engrossed in the life of this world.
As for the worshipers who are solely focused on the Way of Allah, they [struggle] with two other kinds of veils:
The first is the whispering which diverts the heart from thinking about one’s intention. How was it at the beginning? Is it still there now? Is there still sincerity now? That is if he were in prayer.
Another type of whispering is that which diverts your focus to correct the pronunciation of the letters, which leads to doubt and repetition.
This happens in prayer and outside of it [as well]. How can the secrets of the Kingdom be seen by a heart that is focused [only] on how the lips open and close, and how the tongue and jaws move, and how air passes through them?
2- Limiting oneself to the apparent meanings of the Quran
The second kind of veil the worshiper faces is limiting oneself to the apparent meanings of the Quran. This truly inhibits understanding… [because] the truth that Allah has ordered His servants to believe in is of degrees; it has both an apparent meaning (like an outer skin) and a deep internal meaning, which is like the marrow.
For example, [Allah] has ordered His creation to believe that He can be seen; however, seeing has an external and internal [meaning].
If one believes that seeing Allah is similar to the seeing humans are accustomed to in this world, how can he expect to know the secret of Allah’s saying: “You will not see Me…” (Quran 7:143)?!
And how will he understand that is impossible in this life with this eye that is limited to seeing directions and sides?! And how will he understand His saying: “Vision perceives Him not” (Quran 6:103) side-by-side with His saying: “[Some] faces, that Day, will be radiant. Looking at their Lord” (Quran 75:22-23)?!
5- Capture the Lights of the Quran
That you do not limit yourself to capturing the lights [of the Quran], but also glean the appropriate conditions and effects. So, don’t read a verse except that you become adorned with its characteristics.
That way, you will have a certain understanding and overall state for every verse you read.
So, when mercy and the promise of forgiveness are mentioned, you become elated with happiness; when anger and harsh punishment are mentioned, you cringe and become overtaken with fear; at the mention of Allah (Glory be to Him), His Names and His Greatness, you lower your head and feel miniscule—as if you’re vanishing from witnessing His Glory; at the mention of the disbelievers, and Allah’s Exaltedness above having a son and spouse, you bow your head and lower your voice, as if hiding from shame…
These effects should also show on your limbs, as with crying out of sadness, sweating at the forehead from shame, shuddering and shivering in awe of His Glory, and feeling joy in the limbs, tongue and voice when given glad tidings, and feeling fear in them [when being warned].
If you do that, all your parts take part in receiving the barakah (blessings) of the Quran.
Excerpted from Kitāb al-Arba`īn fī Usūl al-Dīn by Imam Abu Ḥamid al-Ghazali.