Grammar term · I'rab · The signs
Retention of nun (5 verbs/dual/m-pl)
thubut al-nun
ثُبُوت النُّون
I'rabThe signsadvanced term
In one line
Retention of the nun (ثُبُوت النُّون) is the keeping of the final nun, and it is the rafa marker of the five verbs.
Classical definition
وَأَمَّا النُّونُ فَتَكُونُ عَلَامَةً لِلرَّفْعِ فِي الْفِعْلِ الْمُضَارِعِ إِذَا اتَّصَلَ بِهِ ضَمِيرُ تَثْنِيَةٍ أَوْ ضَمِيرُ جَمْعٍ أَوْ ضَمِيرُ الْمُؤَنَّثَةِ الْمُخَاطَبَةِ.
“The nun is the marker of rafa in the present verb when the dual pronoun, the plural pronoun, or the pronoun of the addressed woman is joined to it.”
Understand it
In the five verbs the familiar damma is impossible, so the nun itself carries rafa: يَعْمَلُونَ is marfu' because its nun stands. The moment أَنْ or لَمْ arrives the nun goes — تَعْمَلُوا — and its absence becomes the new marker. One letter, the whole story.
How to spot it
Recognition test
ـونَ / ـانِ / ـينَ intact on a mudari' = rafa.
In the Qur'an
ٱلَّذِينَ يُؤْمِنُونَ بِٱلْغَيْبِ وَيُقِيمُونَ ٱلصَّلَوٰةَ وَمِمَّا رَزَقْنَٰهُمْ يُنفِقُونَ
Al-Baqarah 2:3 — “Who believe in the Unseen, are steadfast in prayer, and spend out of what We have provided for them;”
يُؤْمِنُونَ keeps its final nun, and that retention is the marker of rafa. Nothing has entered to govern it, so the nun stays.
Study this ayah word by word →Related terms
Common questions
Why is keeping something counted as a marker?
Because for these forms the nun is at risk. Anything that governs the present verb removes it, so its survival is evidence that nothing has governed the verb — and that is precisely what rafa means for this group of forms.
Next in the guideفِي مَحَلّ جَرّIn place of jarr →Updated