Q: What is the origin of the practice of reciting "Jesus, forgive us our sins ..." in relation to the Rosary?

A: This adjunction at the end of each mystery has its origin in the Marian apparitions of Fatima.  On July 13, 1917, the date which corresponds to the third Fatima apparition, Our Lady is said to have taught the seers the following: When you recite the rosary, after each mystery say, "Oh my Jesus, forgive us our sins, save us from the fires of hell; lead all souls to heaven, especially those most in need of mercy."  Widespread and popular, this prayer, which is attributable to Mary directly, and thus took on special importance and authority, has not been sanctioned by the Church as far as is known to us.  In other words, it is not mandatory for the recitation of the rosary, but represents a practical complement to the second half of the Hail Mary.  It is in tune with the overall thrust of Fatima spirituality.