«وسور السالبة الجزئية فيهما «قد لا يكون»»
For a particular negative conditional—connective or disjunctive—the marker is qad lā yakūn.
It denies the relevant conditional relation in some suppositions. This is weaker than denying it in every case, because a particular negative does not exclude the relation from the entire domain.
Qad yakūn — the relation obtains in some cases.
Qad lā yakūn — the relation fails in some cases.
The negative particle changes the quality to negative while leaving the quantity particular.