A Story
於 = in/concerning(方 square)
事 = matter/incident
無 = not
補 = mend/help (衤clothes)
One cannot go back to a specific time and place in the past to mend a situation. What has already happened, cannot be helped.
Date Added: 3/14/2021
於事無補
a time passed, cannot be cured
Yale: yū sih mòuh bóu
Jyutping: jyu1 si6 mou4 bou2
Sydney Lau: yue1 si6 mo4 bo2