St. Alphonsus Liguori relates a story about St. Dominic and the Rosary which strains credulity to the breaking point. Ultimately this story can be traced back to Bl. Alanus de Rupe.

Alanus de Rupe, or Alanus de la Roche, Dominican, tireless promoter of the Rosary, d. 1475.

Biography of Bl. Alanus de Rupe, also known as Alan or Alain. His cultus has never officially been approved, but he is customarily given the honorific "Blessed."

The fourth chapter of St. Louis de Montfort's book "The Secret of the Rosary." About Bl. Alan de la Roche.