Sun and Moon Letters in Tajweed: When to Say the Lam of Al

Almost every page of the Quran has the word al (ال, "the"). Sometimes you hear its lam clearly, as in al-hamdu. Sometimes it disappears, as in ar-rahman. The rule that decides this is called the rule of the sun and moon letters, and it is one of the first tajweed rules every beginner should learn.

This guide explains what the sun and moon letters are, how to tell them apart, and how to practise them.

What are the sun and moon letters?

When the article ال comes before a word, the letter right after the lam decides how you pronounce it:

• Moon letters (al-huruf al-qamariyyah): the lam is pronounced clearly with a sukoon. This is called izhar qamari.
• Sun letters (al-huruf al-shamsiyyah): the lam is silent, and the next letter is doubled (it carries a shaddah). This is called idgham shamsi.

The names come from two words in Arabic: الْقَمَر (al-qamar, the moon), where the lam is heard, and الشَّمْس (ash-shams, the sun), where it is not.

Surah Ash-Shams shows both in its first two verses:

• وَالشَّمْسِ وَضُحَاهَا — wash-shamsi wa duhaha, the lam is silent (91:1)
• وَالْقَمَرِ إِذَا تَلَاهَا — wal-qamari idha talaha, the lam is clear (91:2)

The 14 moon letters

The moon letters are collected in the phrase ابْغِ حَجَّكَ وَخَفْ عَقِيمَهُ (ibghi hajjaka wa khaf ‘aqimah).

In most printed Mushafs, the lam before a moon letter has a small sukoon on it. That is your visual clue to pronounce it.

The 14 sun letters

The sun letters are the other 14 letters: ت ث د ذ ر ز س ش ص ض ط ظ ل ن.

In the Mushaf, the lam before a sun letter has no mark, and the next letter has a shaddah. No mark on the lam plus a shaddah after it means: skip the lam and double the next letter.

Examples from Surah Al-Fatiha

Surah Al-Fatiha has both kinds, so it is perfect for practice (1:1–7):

• الرَّحْمَٰنِ الرَّحِيمِ — sun letter ر: ar-rahmanir-rahim
• الْحَمْدُ — moon letter ح: al-hamdu
• الْعَالَمِينَ — moon letter ع: al-‘alamin
• الدِّينِ — sun letter د: ad-din
• الصِّرَاطَ الْمُسْتَقِيمَ — sun letter ص, then moon letter م: as-sirat al-mustaqim
• الضَّالِّينَ — sun letter ض: ad-dallin

What happens to the alif at the start?

The alif at the start of ال is a hamzat al-wasl (a "connecting" hamza):

• If you start reading on the word, you pronounce it as a: al-hamdu, ar-rahman.
• If the word comes in the middle of your reading, you skip the alif and join to the word before: bismillahir-rahmanir-rahim, not bismillahi ar-rahman.

Common mistakes

• Pronouncing the lam before a sun letter. Saying al-rahman instead of ar-rahman, or al-nas instead of an-nas.
• Dropping the lam before a moon letter. Saying aq-qamar instead of al-qamar.
• Forgetting the doubling. With sun letters, the next letter must be held a little, like any shaddah. With ن (as in an-nas), this also means a ghunnah of two counts.
• Applying the rule to other lams. This rule is only for the lam of ال. A lam that belongs to the word itself, like in قُلْ (qul) or أَلْهَاكُمُ (alhakum, 102:1), follows other rules.

How to practise

1. Open Surah Al-Fatiha and circle every ال.
1. For each one, look at the next letter. Is the lam marked with a sukoon (moon) or is the next letter doubled (sun)?
1. Read the surah slowly, focusing only on this rule.
1. Move on to Surah An-Nas and Surah Al-Falaq, which repeat an-nas and al-falaq many times.

Once this rule feels natural, move on to the rules of noon sakinah and ghunnah. You can see the full order in our Tajweed guide, or learn with live correction in our online Tajweed course.