هُوَ الْمُسْنَدُ إِلَيْهِ بَعْدَ دُخُولِهِمَا.
Translation: After either particle enters, the noun about which the predicate is stated is its ism.
Musnad ilayh is the entity about which a predicate is asserted. It is not the predicate itself.
Opening interactive controls...
The Author’s Definition
Ism of Mā and Lā Resembling Laysa; Khabar of Lā of Generic Negation
هُوَ الْمُسْنَدُ إِلَيْهِ بَعْدَ دُخُولِهِمَا.
Translation: After either particle enters, the noun about which the predicate is stated is its ism.
Musnad ilayh is the entity about which a predicate is asserted. It is not the predicate itself.