Save it for a rainy day
Does anyone know where this expression comes from?
It's very old.
SAVE FOR A RAINY DAY - "Put something aside against a time of need or adversity. The maxim was around in 1580, when it was put as follows in 'The Bugbears': 'Wold he haue me kepe nothing against a raynye day?'" From The Dictionary of Cliches by James Rogers (Ballantine Books, New York, 1985).