One never prays Mary in vain

In 1749, a great and desperate sinner, in the kingdom of Valencia, in order to escape justice, had resolved to become a Turk, and was actually going to embark, when by chance he passed a church, in which Father Jerome Lopez, of the Company of Jesus, was preaching, and preaching of the divine mercy.

By that preaching he was converted, and confessed to the father, who inquired of him if he had practiced any devotion, for which God had shown towards him that great mercy.

He answered that he had practiced no other devotion than praying the Holy Virgin every day not to abandon him.

Alphonsus Liguori, The Glories of Mary