老後に備えなければならない。

old age

at (place, time); in; on; during; to (direction, state); toward; into; for (purpose); because of (reason); for; with; by; from; as (i.e. in the role of); per; in; for; a (e.g. "once a month"); and; in addition to; if; although

to furnish; to provide for; to equip; to install; to have ready; to prepare for; to possess (all that is needed); to be endowed with; to be armed with; to be born with; to have since birth