also: ずんば · ずは
expression
Archaic conditional expression attached to the -nai stem of a verb. Equivalent to modern なければ or なくては. Found in classical Japanese and set phrases.
「急がずば、濡れざらまし」という古い言い回しがある。
There is an old saying: 'If you do not hurry, you will not get wet.'
古文では「行かずばなるまい」のように使われた。
In classical Japanese, it was used like 'I must go' (literally: if I do not go, it will not do).
Derived from the classical negative auxiliary ず combined with the conditional particle ば. The variant ずんば inserts an epenthetic ん, and ずは is an older form where は was used conditionally.