What is the excepted noun (mustathnā)?
A statement is made about a group, then one member is pulled out of it. The one pulled out is the مُسْتَثْنَى; the group is the مُسْتَثْنَى مِنْهُ; and the tool that does the pulling is إِلَّا or one of its sisters.
| # | Meaning | What it is | ||
|---|---|---|---|---|
| 1 | إِلَّا | illā | except | a particle — the primary tool |
| 2 | غَيْر | ghayr | other than | an ism — takes the i'rab the mustathnā would have had |
| 3 | سِوَى | siwā | other than | an ism — works exactly as غَيْر does |
| 4 | خَلَا | khalā | excepting | used either as a verb or as a preposition |
| 5 | عَدَا | 'adā | excepting | used either as a verb or as a preposition |
| 6 | حَاشَا | ḥāshā | excepting | used either as a verb or as a preposition |
With إِلَّا the excepted word carries the i'rab. With غَيْر and سِوَى the reverse happens: they carry it, and the word after them is always majrūr as a muḍāf ilayh.2
حَضَرَ الطُّلَّابُ إِلَّا مُحَمَّدًا (ḥaḍara al-ṭullābu illā muḥammadan) — the students came, except Muhammad.
The group is named, the tool pulls one out, and the one pulled out is the mustathnā.
The books make a distinction worth keeping. Speech is تَامّ (complete) when the group is actually named, and نَاقِص (incomplete) when it is not — مَا حَضَرَ إِلَّا مُحَمَّدٌ, only Muhammad came. In the incomplete case the excepted word simply takes whatever i'rab its own role in the sentence requires, and is often not manṣūb at all.
Which is why this twelfth role carries an honest caution in the books themselves: the mustathnā is not always manṣūb. It is counted here because most of the time it is.1
This is the one role in the twelve that is not always in nasab — and the books say so themselves.
When the group is named and the sentence is affirmative, the mustathnā is manṣūb: حَضَرَ الطُّلَّابُ إِلَّا مُحَمَّدًا.
When the group is not named, the word takes whatever its own role demands, and is commonly marfū': مَا حَضَرَ إِلَّا مُحَمَّدٌ — here مُحَمَّدٌ is simply the doer of حَضَرَ.
It is kept among the twelve anyway, because most of the time it is manṣūb.
- تَسْهِيل النَّحْو (Tasheel al-Nahw) keeps the mustathnā in the list of twelve and notes plainly that there are exceptions to the rule — it is listed because in most cases it is manṣūb. ↩
- The six tools, and the rule that غَيْر and سِوَى take the ruling the excepted noun would have had, follow اَلنَّحْو التَّطْبِيقِي (an-Naḥw at-Taṭbīqī). ↩