Allah Ta’ala says

وَإِذْ أَخَذَ رَبُّكَ مِنْ بَنِي آدَمَ مِنْ ظُهُورِهِمْ ذُرِّيَّتَهُمْ وَأَشْهَدَهُمْ عَلَى أَنْفُسِهِمْ ألَسْتُ بِرَبِّكُمْ قَالُوا بَلَى شَهِدْنَا أَنْ تَقُولُوا يَوْمَ الْقِيَامَةِ إِنَّا كُنَّا عَنْ هَذَا غَافِلِينَ

"When thy Lord drew forth from the children of Adam from their loins-their descendants and made them testify concerning themselves (Saying)”Am I not your lord (Who cherishes and sustains you) ? They said: Yea! We do testify (this) lest Ye should say on the Day of Judgment of this we were never mindful.” (7:172)

This verse provides an ample evidence of the fact that Allah Ta’ala has inculcated in the genes of a man the capacity necessary to recognize the Oneness of Allah Ta’ala, His supreme authority and the only Sustainer and Cherisher of the World. It is only after this highest spiritual capability given to Adam and his sons that Allah Ta’ala asked them to testify this.

There have been great men in the Islamic history like Zunun-Misri (RA) etc. who vividly recollected this day of covenant as if it had happened just that day itself. Zunun-Misri (RA), when asked if he remembered the covenant used to say:

“The scene of that Covenant is still in front of my eyes, the sound of those words is still ringing in my ears as if it has happened today itself.”

Since man, with all his excellences, is forgetful as well, so Allah Ta’ala sent His Messengers (AS) to this world to remind the mankind of this covenant which is already in its genes. Rasulullah (Sallallahu Alaihi Wasallam) said in a hadith:

"every child is born on the nature of Islam. His parents make him Jew, Christian or worshiper of fire”. (Bukhâri & Muslim Sharief)

The latent qualities of man in the light and darkness

Allah Ta’ala says in the Qur’ân:

أَفَمَنْ شَرَحَ اللَّهُ صَدْرَهُ لِلْإِسْلَامِ فَهُوَ عَلَى نُورٍ مِنْ رَبِّهِ فَوَيْلٌ لِلْقَاسِيَةِ قُلُوبُهُمْ مِنْ ذِكْرِ اللَّهِ أُولَئِكَ فِي ضَلَالٍ مُبِينٍ

“Is one whose heart Allah Ta’ala has opened to Islam, so that he received light from Allah Ta’ala. (No better than one hard hearted)? Woe to those whose hearts are hardened against the remembrance, of Allah Ta’ala! They are manifestly wandering (in error)”. (39:22)

It is patently clear that knowledge of these things has been given to man and that he has been selected for the expression of all the Attributes of Allah Ta’ala and thus we have also come to know that man was busy in Mushahidah Haq in Aalam-i-Arwah and that he has recognised and testified that Allah Ta’ala is his Sustainer, his Cherisher and One and the Only one Lord worth worshipping. When man is born and comes to this universe, these all qualities remain latent or concealed in him. In the verses of the Qur’ân quoted above, (Is one whose heart Allah Ta’ala has opened to Islam, so that he has received light from Allah Ta’ala? Allah Ta’ala again refers to these qualities of heart (Qalb). Those who receive the Divine Light, their latent qualities of Qalb get awakened and enlightened and thus become manifested. Their Qalb starts functioning in the presence of this Divine Light and becomes Muslim i.e., they understand the Qur’ân and recognise their Creator, Sustainer and Cherisher, Allah Ta’ala the Almighty and the Exalted.

Those who do not receive this Divine Light, their latent qualities of Qalb do not get manifested, they remain in darkness and in the process their Qalb fails to function and hence neither understand the Qur’ân nor recognise their Creator, Sustainer, Cherisher, Allah Ta’ala the Almighty and the Exalted. Allah Ta’ala calls these hearts as hardened. They remain in darkness and fail to expand their spiritual understanding and to receive Allah Ta’ala's Light. They travel in opposite direction. Just as there is spiritual progress for those who seek Allah Ta’ala, on the other hand there is more and more spiritual retrogression for those who close their hearts to Allah Ta’ala. Their hearts get hardened, and they allow less and less Allah Ta’ala's Grace to penetrate within. But it is obvious that they flounder on the way and cannot walk with the firm steps of those whose hearts abound in faith.

It is, therefore, well said: Hardened hearts are the most hated things near Allah Ta’ala. Allah Ta’ala taught us this Dua in the Qur’ân:

رَبَّنَا لَا تُزِغْ قُلُوبَنَا بَعْدَ إِذْ هَدَيْتَنَا وَهَبْ لَنَا مِنْ لَدُنْكَ رَحْمَةً إِنَّكَ أَنْتَ الْوَهَّابُ

“O Lord! they say, let not our hearts deviate. Now after Thou has guided us, But grant us mercy from Thee. For Thou art the grantor of bounties without measure." (3:8)

Qalb-i-Saleem (Safe heart):

Allah Ta’ala further says in the Qur’ân:

إِلَّا مَنْ أَتَى اللَّهَ بِقَلْبٍ سَلِيمٍ

“But only he (will prosper) that brings to Allah Ta’ala a sound heart”. (26:89)

For real prosperity you need a properly functioning heart that is liked by Allah Ta’ala. Saleem is a word derived from Salaamat. It is a broad term but we can translate it as 'safe', also. Qalb is necessary for the real prosperity and safe Qalb is liked by Allah Ta’ala.

The safe Qalb means that all the qualities (latent or manifest) that have been given to it, are not wasted. The immense potential, which Allah Ta’ala has bestowed to the human Qalb is intact and well used and not disused.

It was already mentioned that man has been selected for expression of all the Attributes of Allah Ta’ala. Man's Qalb is framed to accommodate the faculties of quite different and opposing nature, as man is a mixture of opposites. If each faculty of Qalb remains in its right proportion and limits and each does its job in a just manner, it can be called as Saleem (safe). What is safe, is sound and healthy as well. If it is not safe, it is not sound and healthy i.e., it is diseased. When it is diseased, it stops doing its function. It is the king of all parts of the body and when the king becomes defunct one can imagine the fate of the nation (the man).

Rasulullah (Sallallahu Alaihi Wasallam) says:

ألا وإنّ في الجَسَدِ مُضْغَةً إذا صَلَحَتْ صَلَحَ الجَسدُ كُلُّهُ وإذا فَسَدَتْ فَسَدَ الجَسَدُ كُلُّهُ ألا وهْيَ القَلبُ

“ Indeed there is a piece of flesh in the body (the heart) when that stays right, the whole body stays right, when that goes astray, the whole body goes astray! Listen with open ears, that is Qalb” (Bukhâri Sharief)

When the king is in right condition and functions properly, the subjects will be in right condition and they will also function properly and vice versa.

The most blessed Qalb which got the highest expansion and elevation

In the human history the most blessed Qalb which Allah Ta’ala selected for the highest purification, expansion and elevation was that of Muhammad-ur-Rasulullah (Sallallahu Alaihi Wasallam).

Allah Ta’ala says in the Qur’ân:

أَلَمْ نَشْرَحْ لَكَ صَدْرَكَ

“Have We not expanded thee thy breast?”. ( 94:1)

The breast is symbolically the seat of knowledge and the highest feelings of love and affection. It is the treasure house in which are stored the jewels of that quality of human character, which is divine. The Holy Prophet’s (Sallallahu Alaihi Wasallam) human nature had been purified, expanded and elevated, so that he became the mercy for all the creation.

The Qalb of Rasulullah (Sallallahu Alaihi Wasallam) which is the most blessed got the highest Divine Light and he utilised the capabilities of Qalb to its maximum. All the latent faculties of Qalb got the highest illumination by the Divine Light and thus Rasulullah (Sallallahu Alaihi Wasallam) attained the highest spiritual understanding and nearness to the ultimate Reality.

The Qur’ân is the Attribute of Allah Ta’ala and that the Attributes of Allah Ta’ala are immense and ultimate. Nothing in this universe had the capability of receiving this Divine Revelation. The Qalbs of all the men except that of Rasulullah (Sallallahu Alaihi Wasallam) could not attain this spiritual height which was necessary for being capable of receiving this divine revelation i.e., the Qur’ân. The Qalb of Rasulullah (Sallallahu Alaihi Wasallam) being the most blessed had this capability. It is said that if Allah Ta’ala would have sent this revelation directly to this universe, it would have got burnt down to ashes.

Allah Ta’ala had decided to express His divine revelation, He created this capability in the most blessed Qalb of Rasulullah (Sallallahu Alaihi Wasallam).

Allah Ta’ala refers to this the most blessed Qalb of Rasulullah (Sallallahu Alaihi Wasallam) as follows:

وَإِنَّهُ لَتَنْزِيلُ رَبِّ الْعَالَمِينَ () نَزَلَ بِهِ الرُّوحُ الْأَمِينُ () عَلَى قَلْبِكَ لِتَكُونَ مِنَ الْمُنْذِرِينَ ()

"Verily this is a revelation from the Lord of the worlds. With it came down the truthful spirit To thy heart that thou mayest admonish." (26:192-194)

Qalb signifies not only the seat of affection, but also seat of memory and understanding. The process of inspiration is indicated by the impression of the divine message on the inspired one’s heart, memory and understanding from which it was promulgated in human speech to the world.

It is said that Jalaal of the Divine Revelation was tolerated and absorbed by the Qalb of Rasulullah (Sallallahu Alaihi Wasallam) which alone is the most blessed and when it was expressed through the blessed tongue of Rasulullah (Sallallahu Alaihi Wasallam) it is was Jamaal only, which the rest of the humanity and this universe could tolerate.