sackcloth and ashes
Noun
Meaning
a display of extreme remorse or repentance or grief
Source: WordNetSynonyms
cypress
penitence
flagellation
fasting
repentance
penance
remorse
expiation
mortification
contrition
maceration
purgation
shrift
Hypernyms
Examples
Consequently, he left in anger, rebuking the three places saying: “Woe to you, Chorazin, Bethsaida, and Capernaum, for if I had done these mighty works in the sinful cities of Tyre and Sidon, they would have repented in sackcloth and ashes.”
For if the deeds of power done in you had been done in Tyre and Sidon, they would have repented long ago in sackcloth and ashes.