I’m typically the guy who says: “Why carry a nail? It’s too heavy! … We probably won’t need it on this trip.” 😀
The proverb is found in a number of forms, beginning as early as the 13th century.
For want of a nail the shoe was lost.
For want of a shoe the horse was lost.
For want of a horse the rider was lost.
For want of a rider the message was lost.
For want of a message the battle was lost.
For want of a battle the kingdom was lost.
And all for the want of a horseshoe nail.
Related sayings are “A stitch, in time, saves nine” and “An ounce of prevention is worth a pound of cure”.