My father's habit was always to say, 'Time is money.'
Literal
Father [topic-は] time [topic-は] money is [quotative-と] say [nominalizer-の] [subject-が] constant was [polite-でした].
~のが常でした means 'it was always the case that / it was his custom to.' 常 (つね) means 'constant/regular.' The quoted 時は金なり uses the classical copula なり (= modern だ/である), lending the proverb a timeless, authoritative feel.