What is the explanatory apposition ('atf bayan)?
In one line
Classical definition
Understand it
أَقْسَمَ بِاللهِ أَبُو حَفْصٍ عُمَرُ — Abu Hafs, Umar, swore by Allah. عُمَرُ does not describe Abu Hafs; it identifies him.
That is the work of the عَطْف بَيَان: it follows a noun and makes plain who or what is meant, using a name rather than a quality — and no particle stands between them.
The followers
A follower has no i'rab of its own. It copies the word before it — which is why the followers sit outside the twenty-two roles.
It behaves exactly like a نَعْت in following its noun through i'rab, definiteness, number and gender. The difference is what it is made of: a na't is a description, an 'atf bayan is a naming.
And it sits very close to the بَدَل — close enough that the grammarians argue about the boundary.1
How to spot it
Telling it apart from a badal
Both a بَدَل and an عَطْف بَيَان are a second noun, with no particle between, taking the same i'rab.
The usual test: a badal is the word actually intended — drop the first and the sentence still stands. An 'atf bayan works together with the first rather than replacing it.
Related terms
Common questions
How is this different from a badal?
The two overlap enough that grammarians dispute individual cases. The usual line is that an 'atf bayan clarifies which one is meant while staying subordinate, whereas a badal is the word the sentence really intends and could stand in its place alone.
Next in the guideعَطْفُ النَّسَقWhat is the conjunctive follower ('atf nasaq)? →Notes
- This guide counts five followers, following تَسْهِيل النَّحْو (Tasheel al-Nahw). اَلنَّحْو التَّطْبِيقِي (an-Nahw at-Tatbiqi) and the Arabic Tutor count four and leave the 'atf bayan out — the Arabic Tutor does not mention it once in four volumes. They treat what it covers as a kind of بَدَل. The practical difference between the two is thin. ↩
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