Grammar term · Nahw · syntax
الْتِقَاء السَّاكِنَيْن
iltiqa' al-sakinayn
Two-quiescents resolution
Nahw · syntaxOperationadvanced term2,168+ in the Qur'an
In one line
Two silences colliding: Arabic never voices two sukuns in a row — one letter drops or takes a helping vowel: قُمِ ٱلَّيْلَ.
Classical rule
الْتِقَاءُ السَّاكِنَيْنِ تَوَالِي حَرْفَيْنِ سَاكِنَيْنِ، يُتَخَلَّصُ مِنْهُ بِحَذْفِ أَحَدِهِمَا أَوْ تَحْرِيكِهِ بِالكَسْرِ غَالِبًا.
“The meeting of two sakins is the succession of two vowel-less letters; it is resolved by deleting one of them or by moving a vowel in.”
(بتصرف من شذا العرف)
Key words in the Arabic
تَوَالِيthe following in succession
يُتَخَلَّصُ مِنْهُit is escaped by
Understand it
The rule explains a hundred small surprises. Why قُمِ ٱلَّيْلَ with a kasra on the mim? — the amr's sukun met the wasl-sukun of ٱل, and a kasra broke the clash. Why does لَمْ يَقُلْ lose its long vowel? — the alif of قَالَ was silently long, jazm added a second sukun, and the long vowel dropped. Wherever an ending suddenly gains a vowel before ٱل, or a long vowel shortens, two sakins have met and been separated.
How to spot it
Recognition test
A sukun-ending word followed by hamzat al-wasl, or a jazm/sukun ending on a hollow or long-vowel form: expect a helping kasra (sometimes damma: قَالُوا۟ ٱدْعُ) or a shortened vowel.
In the Qur'an
قُمِ ٱلَّيْلَ إِلَّا قَلِيلًا
Al-Muzzammil 73:2 — “Stand in prayer through the night, except a little”
قُمْ + ٱلَّيْلَ = two sakins meeting; the mim takes a kasra to break the collision.
Related terms