What is the khabar of lā of absolute negation?

There is a لَا that does not merely say not — it denies the whole kind. لَا رَجُلَ فِي الدَّارِ (lā rajula fī al-dāri) does not say “a man is not in the house”; it says there is no man in the house at all. That is why it is called لَا لِنَفْيِ الْجِنْسِ, the لَا that negates the class.

The noun straight after it — رَجُلَ — is its اِسْم. It takes a single fatḥa, with no tanwīn and no الـ. It belongs to the manṣūbāt.

The word اِسْتِغْرَاق (istighrāq) is the one the books use for what it does: it sweeps the whole class up, leaving nothing out.

What is then said about the noun is its خَبَر, and that stays marfū' — which is why it belongs here, among the eight.

The noun drops into nasab without tanwīn; the khabar reporting about it stays in rafa.

In لَا طَالِبَ حَاضِرٌ (lā ṭāliba ḥāḍirun), no student is present, طَالِبَ is the ism in nasab and حَاضِرٌ is the khabar in rafa.

The khabar is often a phrase rather than a single word — فِي الدَّارِ in the first example above — and in the most familiar sentence of all, لَا إِلٰهَ إِلَّا اللهُ, it is left unspoken and understood.

Do not confuse this لَا with the لَا that resembles لَيْسَ.

لَا لِنَفْيِ الْجِنْسِ puts its noun in nasab, with a bare fatḥa and no tanwīn — لَا رَجُلَ فِي الدَّارِ.

لَا الْمُشَبَّهَة بِلَيْسَ leaves its noun in rafa and puts its khabar in nasab.

The two conditions in the classical definition are the test: the لَا must come directly upon the indefinite noun, and it must not be repeated.