Presenting here, with sparse context, three interlocking adages:

1) a little Neglect may breed great Mischief
(Farrier website¹ paraphrasing Ben Franklin² translating older sources³):

For the want of a nail the shoe was lost,
For the want of a shoe the horse was lost,
For the want of a horse the rider was lost,
For the want of a rider the battle was lost,
For the want of a battle the kingdom was lost,
And all for the want of a horseshoe-nail.

2) Old Man of the Frontier Loses Horse
(ctext translation⁴ of Huainanzi⁵ )

The transformation between misfortune and fortune is interdependent;
its changes are hard to foresee.
There was a man near the frontier who was good at divination;
his horse suddenly disappeared and ran into Hu territory.
People all came to console him.
His father said: “How do we know this is not a blessing?”

After several months, his horse returned with a fine Hu horse.
People all came to congratulate him. His father said:
“How do we know this will not bring misfortune?”
With many fine horses in the household, his son liked to ride;
he fell and broke his thigh. People all came to console him again.
His father said: “How do we know this is not actually a blessing?”

After one year, the Hu people launched a large-scale invasion of the frontier.
The strong and vigorous drew their bows to fight;
among those near the border, nineteen out of twenty died.
Only because this man’s son was lame did father and son manage to protect each other and survive. Therefore, blessings may turn into misfortunes, and misfortunes may become blessings; the transformation is boundless and unfathomably deep.

3) May you live in interesting times
(Terry Pratchett⁶ embellishing an apocryphal malediction⁷)

I believe that the phrase is “may you live in interesting times,”
and is the lowest in a trilogy of Chinese curses that continue
“may you come to the attention of those in authority” and finish with
“may the gods give you everything you ask for.”
I have no idea about its authenticity.

References:
1) https://butlerprofessionalfarrierschool.com/archives/2110
2) https://founders.archives.gov/documents/Franklin/01-07-02-0146
3) https://en.wikipedia.org/wiki/For_want_of_a_nail#History
4) https://ctext.org/huainanzi/ren-xian-xun#n3395
5) https://en.wikipedia.org/wiki/The_old_man_lost_his_horse
6) https://www.washingtonpost.com/wp-dyn/content/discussion/2008/09/25/DI2008092502168.html
7) https://en.wikipedia.org/wiki/May_you_live_in_interesting_times
image: https://upload.wikimedia.org/wikipedia/commons/0/07/1_Zhao_Mengfu_Man_Riding_a_Horse%2C_dated_1296_%2831.5_x_620_cm%29_Palace_Museum%2C_Beijing.jpg