一失足成千古恨

yīshīzúchéngqiāngǔhèn ㄧ ㄕ ㄗㄨˊ ㄔㄥˊ ㄑㄧㄢ ㄍㄨˇ ㄏㄣˋ

    • a single slip may cause everlasting sorrow (idiom)

Character by character

Sources