At Lourdes, during the ninth apparition of Mary to Bernadette on February 25, 1858, the Virgin Mary called for penance. Three hundred people were present.
Bernadette recalled: "She told me to go and drink from the spring ... I found only a little muddy water. On the fourth try I managed to drink. She also made me eat a plant that was near the fountain, then the vision disappeared and I went away."
The plant, golden saxifrage, had a bitter taste. The water was dirty, and Bernadette's face was smeared. Her most fervent supporters were shocked.
Onlookers asked her: "Do you know that people think you're crazy for doing things like this?" She replied, "It's for sinners."
The Virgin Mary would repeat the same messages:
"Penance! Penance! Penance!"....;
"Pray to God for sinners.";
"Go and kiss the ground as a penance for the conversion of sinners."
The following February 27 was the tenth apparition: Bernadette again performed penitential acts (kissing the earth, eating bitter herbs, drinking water).
Source: Marian Encyclopedia