The Nail by Brothers Grimm
A merchant had done good business at the fair; he had sold his wares,
and lined his money-bags with gold and silver. Then he wanted to travel
homewards, and be in his own house before nightfall. So he packed his
trunk with the money on his horse, and rode away.
At noon he rested in a town, and when he wanted to go farther the
stable-boy brought out his horse and said, "A nail is wanting, sir, in the
shoe of its left hind foot." "Let it be wanting," answered the merchant;
"the shoe will certainly stay on for the six miles I have still to go. I
am in a hurry."
In the afternoon, when he once more alighted and had his horse fed,
the stable-boy went into the room to him and said, "Sir, a shoe
is missing from your horse's left hind foot. Shall I take him to the
blacksmith?" "Let it still be wanting," answered the man; "the horse can
very well hold out for the couple of miles which remain. I am in haste."
He rode forth, but before long the horse began to limp. It had not limped
long before it began to stumble, and it had not stumbled long before it
fell down and broke its leg. The merchant was forced to leave the horse
where it was, and unbuckle the trunk, take it on his back, and go home
on foot. And there he did not arrive until quite late at night. "And
that unlucky nail," said he to himself, "has caused all this disaster."