First: Definition and Letters of Idghām
Idghām is the merging of nūn sākinah or tanwīn into one of the idghām letters when it follows in the next word. The idgham letter following the nūn is doubled.
The six idghām letters are: yāʼ, rāʼ, mīm, lām, wāw, and nūn. They are collectively represented in the word: **“Yarmilūn”**”يرملون”.
If any of these letters follow a nūn sākinah or tanwīn at the end of a word, idghām must be applied on one condition which is that the nūn sākinah is at the end of the first word and Idgham letter is at the beginning of the next word. ¹
Second: Types of Idghām
1. Idghām with Ghunnah (nasalization):
This type involves a ghunnah of two counts. Its letters are four: yāʼ, nūn, mīm, and wāw—represented by the word: **“Yanmu”**”ينمو”.
Example: ﴿فَمَن يَعۡمَلۡ﴾ →the nūn is merged into yāʼ then we pronounce a double yāʼ like this: (famay-yaʿmal)(فميّعمل) with ghunnah of 2 counts on the assimilated yāʼ. ²
Examples of Idghām with Ghunnah:
| Letter | With Nūn | With Tanwīn |
| Yāʼ | ﴿إِن يَقُولُونَ﴾ | ﴿يَوۡمَئِذٖ يُوَفِّيهِمُ﴾ |
| Nūn | ﴿إِن نَّقُولُ﴾ | ﴿مَلِكٗا نُّقَٰتِلۡ﴾ |
| Mīm | ﴿مِن مَّآءٖ﴾ | ﴿كِتَٰبٖ مُّبِينٖ﴾ |
| Wāw | ﴿مِن وَرَآءِ﴾ | ﴿إِلَٰهٗا وَٰحِدٗا﴾ |
2. Idghām without Ghunnah: This type of idgham is not accompanied by ghunnah and is specific to two letters: lām and rāʼ.
ونبين ذلك بمثال: فعند إدغام النون الساكنة في اللام في قوله تعالى: ﴿مِن لُّغُوبٖ﴾، فإننا نقلب النون لامًا مشددة من غير غنة، هكذا: (مِلُّغُوبٖ).
Examples of Idghām without Ghunnah:
| Letter | With Nūn | With Tanwīn |
| Rāʼ | ﴿مِن رِّزۡقِ﴾ | ﴿رَءُوفٞ رَّحِيمٞ﴾ |
| Lām | ﴿مِن لُّغُوبٖ﴾ | ﴿هُدٗى لِّلۡمُتَّقِينَ﴾ |
Third: Idghām in the Disjointed Letters
Idghām appears in the disjointed letters in two places in the Qur’an: the opening of Surahs Ash-Shuʿarāʼ and Al-Qaṣaṣ with the three letters ﴿طسٓمٓ﴾. The sequence ends with a nūn sākinah in ﴿س﴾ followed by mīm in( مـ) . Since mīm is one of the ghunnah letters the nūn is merged into the mīm, and we apply idghām with ghunnah of two counts, pronouncing it as: (ṭā-simmīm)(طاسيمّيم).⁴
Fourth: Important Notes
1. Idghām only occurs across two words. If both letters are in one word, the nūn is pronounced clearly so we don’t distort its pronunciation and meaning. This is called ** iẓhār Mutlaq**(absolute clarificartion) and occurs in four words in the Qur’an: **dunyā, bunyān, ṣinwān, qinwān**
2. Idghām is not applied in the openings of Surahs Yā-Sīn and Al-Qalam ﴿يسٓ١ وَٱلۡقُرۡءَان﴾ and ﴿ وما يسطروننٓۚ وَٱلۡقَلَمِ﴾, when reading the nūn sākinah in continuation with the following word we notice that it is followed a wāw in both cases which is one of idgham letters (nūn sākinah in (يس) with waw in the beginning of the second verse and nūn sākinah in (ن) and the waw is (والقلم) ) but these two are pronounced clearly without idgham according to Hafs’ narration.⁴
Ar-Riʿāyah (p. 262), At-Taḥdeed (p. 113), Nihāyat al-Qawl al-Mufīd (p. 156), Hidayat al-Qari (1/162), Al-Muneer (p. 139).
Ar-Riʿāyah (p. 262), Nihāyat al-Qawl al-Mufīd (p. 156), Hidayat al-Qari (1/162), Al-Muneer (p. 139).
Ar-Riʿāyah (pp. 263–265), At-Taḥdeed (pp. 115–116), Hidayat al-Qari (1/162), Al-Muneer (p. 139).
Ar-Riʿāyah (p. 265), At-Taḥdeed (pp. 116–117), Nihāyat al-Qawl al-Mufīd (pp. 160–161), Hidayat al-Qari (pp. 163, 165), Al-Tajweed al-Musawwar (p. 134), Al-Muneer (pp. 140–141).