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the rules of the assmilation al idgham

Tajweed rules of the Assimilation of Two letters

Al Idgham

In the rich tapestry of the Arabic language, the term ‘assimilation’ or ‘idgham’ metaphorically captures the essence of one entity merging seamlessly into another.


Within the realm of Tajweed, this signifies the blend of the first letter into the subsequent one. It’s a harmonious convergence where one letter gracefully disappears, enriching the sound of the following.


Three primary forms of al-idgham manifest:


  1. Al-Idgham Al-Mutamathilayn (The Identicals): Here, two letters share both the same point of articulation and characteristics. It’s like a mirror reflection, where ت mirrors ت.
  2. Al-Idgham Al-Mutajanissayn (The Assimilates): These pairs have the same origin of sound but possess distinct attributes. An example would be ت and ط, echoing from the same location but producing contrasting tones.
  3. Al-Idgham Al-Mutaqaribayn (The Proximates): This encompasses pairs of letters which, although not identical, have closely related articulation points and similar attributes. Pairs like س and د or ق and ك demonstrate this closeness.


Moreover, when diving deeper into diverse recitation styles, idgham emerges in two significant variations:


  • Al-Idgham Al-Kabeer (The Grand Assimilation): This reflects a prominent merging of sounds, where the assimilation is quite evident.
  • Al-Idgham As-Sagheer (The Subtle Assimilation): Here, the convergence is gentle, creating a soft blend that’s less pronounced.


The beauty of Tajweed lies in its precision and the harmonious dance of letters, and understanding idgham adds another layer to this intricate dance.

1. Al-Idgham Al-Kabeer: The Grand Assimilation

The Grand Assimilation, Al-Idgham Al-Kabeer, is applied to Al-Mutamathilayn, Al-Mutajanissayn, and Al-Mutaqaribayn when the initial letter is accentuated with a vowel mark.





وَإِذَا النُّفُوسُ زُوِّجَتْ 



And when the souls are paired (81:7)



In the given illustration, the letter س seamlessly melds into the letter ز, effectively rendering it invisible.


This nuanced method of reading is distinctive to the styles of Abi Amroo and Ya’qub, albeit with slight variations between the two.

Contrastingly, in the recitation techniques of Asim and Nafi, this approach diverges. Their rule stipulates that for assimilation to occur, the initial letter must carry a sukoon, or be void of any vowel marks.


2. Al-Idgham As-Sagheer: The Subtle Assimilation

Widely accepted across all recitation styles, Al-Idgham As-Sagheer, or the subtle assimilation, is invoked when letters from the categories of mutamathilayn, mutajanissayn, and mutaqaribayn meet. Specifically, when the initial letter of the pair has a sukoon, it gracefully merges into, or becomes indistinguishable within, the succeeding vocalized (mutaharika) letter.


The nuances of this subtle idgham can be categorized as:


  1. Compulsory: An obligatory assimilation that must be observed.
  2. Permissible: Assimilation that can be exercised based on one’s discretion.
  3. Forbidden: Situations where assimilation must not occur.


The realm of permissible idgham is particularly extensive and varies across different recitation styles, providing a rich tapestry of nuances and interpretations.

A. Al-Idgham Al-Wajib: The Mandatory Assimilation

Let’s delve into a few illustrative examples:


كَلَّا ۖ بَل لَّا تُكْرِمُونَ الْيَتِيمَ



No! But you do not honour the orphan (89:17)




فَإِن كَذَّبُوكَ فَقُل رَّبُّكُمْ ذُو رَحْمَةٍ 



So if they deny you, [O Muhammad], say, “Your Lord is the possessor of vast mercy (6:147)

B. Al-Idgham Al-Mamnoo: The Prohibited Assimilation

As previously discussed, there are instances where idgham is strictly prohibited. Certain scenarios stand as exceptions to the general rules of idgham, disallowing any merger:

Letters of Madd (Prolongation)

Letters of Madd (Prolongation): When the initial letter is one of the letters that cause elongation or prolongation in its pronunciation, assimilation is forbidden.


Let’s explore this through some examples:



تَعْرُجُ الْمَلَائِكَةُ وَالرُّوحُ إِلَيْهِ فِي يَوْمٍ كَانَ مِقْدَارُهُ خَمْسِينَ أَلْفَ سَنَةٍ



The angels and the Spirit will ascend to Him during a Day the extent of fifty thousand years. (70:4)




قَالُوا وَهُمْ فِيهَا يَخْتَصِمُونَ



They will say while they dispute therein, (26:96)




In this context, it’s crucial to uphold the madd (elongation) of the initial letter, ensuring its clear pronunciation. The idgham should not be applied in such instances. Instead, we adhere to the rule of ‘madd at-tamkeen’ for a steady and firm elongation.

When Lam (ل) Encounters Noon (ن): Rules and Pronunciations

Consensus among scholars dictates that assimilation – or idgham – of the letters lam and noon is prohibited, with the sole exception being the Lam in the definite article ال. Let’s delve into some illustrative examples:



 قُلْ نَعَمْ وَأَنتُمْ دَاخِرُونَ



Say, “Yes, and you will be [rendered] contemptible.” (37:18)




قُلْ هَلْ نُنَبِّئُكُم بِالْأَخْسَرِينَ أَعْمَالً




Say, [O Muhammad], “Shall we [believers] inform you of the greatest losers as to [their] deeds? (18:103)

When Lam (ل) Encounters Ta (ت): Rules and Pronunciations




فَالْتَقَمَهُ الْحُوتُ وَهُوَ مُلِيمٌ



Then the fish swallowed him while he was blameworthy. (37:142)

When a Throat-Origin Letter is Followed by a Neighboring Letter: Rules and Nuances



 وَمِنَ اللَّيْلِ فَسَبِّحْهُ وَأَدْبَارَ السُّجُودِ



And [in part] of the night exalt Him and after prostration. (50:40)




وَمِنَ اللَّيْلِ فَسَبِّحْهُ وَإِدْبَارَ النُّجُومِ



And in a part of the night exalt Him and after [the setting of] the stars. (52:49)




 رَبَّنَا لَا تُزِغْ قُلُوبَنَا بَعْدَ إِذْ هَدَيْتَنَا وَهَبْ لَنَا مِن لَّدُنكَ رَحْمَةً ۚ إِنَّكَ أَنتَ الْوَهَّابُ



[Who say], “Our Lord, let not our hearts deviate after You have guided us and grant us from Yourself mercy. Indeed, You are the Bestower. (3:8)


3. Al-Idgham Al-Fard: The Essential Assimilation

In the Hafs recitation, Al-Idgham As-Sagheer is mandated in the following scenarios:

A. Assimilation of Twin Letters: Al-Idgham Al-Mutamathilayn Explained

In the process of assimilation, two letters are indistinguishable, sharing both the same endpoint and identical characteristics.





أَيْنَمَا تَكُونُوا يُدْرِككُّمُ الْمَوْتُ



Wherever you may be, death will overtake you (4:78)




From a technical standpoint, the letter involved in “al-idgham al-mutamathilayn” should be pronounced with the added emphasis associated with the shadda, and when it appears before the letters noon or meem, we should also execute a double-stroke ghunna.

B. The Dual Assimilation: Al-Idgham Al-Mutajanisayn

The two assimilated letter



 وَلَا أَنَا عَابِدٌ مَّا عَبَدتُّمْ



Nor will I be a worshipper of what you worship. (109:4)




فَآمَنَت طَّائِفَةٌ مِّن بَنِي إِسْرَائِيلَ وَكَفَرَت طَّائِفَةٌ



And a faction of the Children of Israel believed, and a faction disbelieved. (61:14)


In the Hafs Quranic recitation style, the rule of “al-idgham al-mutajanisayn” is applied in seven distinct instances:


  • the letter د in the ت




وَعَادًا وَثَمُودَ وَقَد تَّبَيَّنَ لَكُم مِّن مَّسَاكِنِهِمْ



And [We destroyed] ‘Aad and Thamud, and it has become clear to you from their [ruined] dwellings (29:38)




  • the letter ت in the د





فَلَمَّا أَثْقَلَت دَّعَوَا اللَّهَ رَبَّهُمَا لَئِنْ آتَيْتَنَا صَالِحًا لَّنَكُونَنَّ مِنَ الشَّاكِرِينَ



And when it becomes heavy, they both invoke Allah, their Lord, “If You should give us a good [child], we will surely be among the grateful.” (7:189)




  • the letter ت in the ط




إِذْ هَمَّت طَّائِفَتَانِ مِنكُمْ أَن تَفْشَلَا وَاللَّهُ وَلِيُّهُمَا



When two parties among you were about to lose courage, but Allah was their ally; (3:122)




  • the letter ط in the ت




فَمَكَثَ غَيْرَ بَعِيدٍ فَقَالَ أَحَطتُ بِمَا لَمْ تُحِطْ بِهِ وَجِئْتُكَ مِن سَبَإٍ بِنَبَإٍ يَقِينٍ



But the hoopoe stayed not long and said, “I have encompassed [in knowledge] that which you have not encompassed, and I have come to you from Sheba with certain news. (27:22)




In this particular scenario, we apply a milder form of assimilation known as “idgham naqees,” preserving the distinct quality of “al-isti’la” in the pronunciation of the letter “ت” while assimilating it with the letter “ط.




  • the letter ذ in the ظ





وَلَن يَنفَعَكُمُ الْيَوْمَ إِذ ظَّلَمْتُمْ أَنَّكُمْ فِي الْعَذَابِ مُشْتَرِكُونَ 



And never will it benefit you that Day, when you have wronged, that you are [all] sharing in the punishment. (43:39)




  • the letter ث in the ذ




فَمَثَلُهُ كَمَثَلِ الْكَلْبِ إِن تَحْمِلْ عَلَيْهِ يَلْهَثْ أَوْ تَتْرُكْهُ يَلْهَث ۚ ذَّٰلِكَ مَثَلُ الْقَوْمِ الَّذِينَ كَذَّبُوا بِآيَاتِنَا


 So his example is like that of the dog: if you chase him, he pants, or if you leave him, he [still] pants. That is the example of the people who denied Our signs (7:176)




  • the letter ب in the م




وَكَانَ فِي مَعْزِلٍ يَا بُنَيَّ ارْكَب مَّعَنَا وَلَا تَكُن مَّعَ الْكَافِرِينَ



 “O my son, come aboard with us and be not with the disbelievers.” (11:42)


Hence, from a technical perspective, we do not enunciate the initial letter in “al-idgham al-mutajanisayn,” whereas the second letter is articulated with the added emphasis attributed to the shadda.


the two assimilated letter: al idgham al mutaqaribayn

This phenomenon is referred to as such when the two subsequent letters share proximate articulation points yet possess distinct characteristics.


Mandatory mergers occur exclusively in two instances:


  1. The letter ل merging with the letter ر
  2. The letter ق merging with the letter ك





وَقُل رَّبِّ زِدْنِي عِلْمًا



“My Lord, increase me in knowledge.” (20:114)



أَلَمْ نَخْلُقكُّم مِّن مَّاءٍ مَّهِينٍ



Did We not create you from a liquid disdained? (77:20)




When it comes to the merger of the letter ق with the letter ك, there exists a divergence in the choice of idgham to be applied.


Certain scholars advocate for an idgham “naqis,” which involves a slight merging by pronouncing the ك while retaining the distinct characteristic of “isti’ala” from the ق.


On the other hand, some scholars advocate for a pure idgham.


Technically, in the case of “al-idgham al-mutaqaribayn,” the first letter is not articulated separately, but the second letter is pronounced with added emphasis due to the shadda.


This Tajweed rules lesson has concluded. Insha’Allah, the next lesson will cover the rules of the beginning and the rules for stopping during the recitation.


At the Al-dirassa Institute, we provide an accessible path to mastering Tajweed under the guidance of skilled instructors. Should you wish to pursue this further, we warmly invite you to reach out to us.

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