备而不用

have sth ready just in case / keep sth for possible future use

variant of 備|备[bei4]

to prepare / get ready / to provide or equip

(bound form) to prepare; to equip / (literary) fully; in every possible way

and / as well as / and so / but (not) / yet (not) / (indicates causal relation) / (indicates change of state) / (indicates contrast)

no; not so / (bound form) not; un-

need not

to use / to employ / to have to / to eat or drink / expense or outlay / usefulness / hence / therefore