Where does it mention the Rosary in the Bible?

Besides the meditations on the mysteries of Christ and Our Lady (all of which are indicated in Scripture), the Rosary is comprised essentially of two prayers, the Our Father and the Hail Mary.  Both come from the Bible.  The Our Father is given to us by Our Lord in Scripture (Matthew 6; Luke 11), and the main part of the Hail Mary is found in Luke Chapter 1.  The Hail Mary is as follows:  HAIL MARY FULL OF GRACE, THE LORD IS WITH THEE, BLESSED ART THOU AMONG WOMEN AND BLESSED IS THE FRUIT OF THY WOMB JESUS, HOLY MARY MOTHER OF GOD PRAY FOR US SINNERS NOW AND AT THE HOUR OF OUR DEATH.

“Hail [Mary], full of grace, the Lord is with thee, Blessed art thou among women” comes directly from Luke 1:28. “Blessed art thou among women and Blessed is the fruit of thy womb [Jesus]” comes directly from Luke 1:42. “Holy Mary Mother of God pray for us sinners now and at the hour of our death” is not found in Scripture, but completes the above prayer with a sublime petition to the Mother of God.

Protestants fail to understand the significance of Mary because they don’t understand Jesus.  They fail to understand the significance of the following truth about Jesus.

Pope St. Leo the Great, Council of Chalcedon, 451, ex cathedra: “… our Lord Jesus Christ… indeed born of the Father before all ages according to His Divinity, but in the last days born of the Virgin Mary, Mother of God, according to His humanity; for us and for our salvation, one and the same Christ…”

One may say, what is Mary doing in a discussion of this magnitude?  Therein lies her dignity, her power with God, and why God wishes us to have devotion to her.  Catholics perceive and say “wow” at Mary’s role in the above, while Protestants remain blind to it and often attack it.  They fail to understand how her soul “doth magnify the Lord” (Luke 1:47) because they don’t understand who she is who gives birth to the Son of God in His humanity.  They fail to perceive the ramifications of this inscrutable truth. The Hail Mary, which begins in Luke 1:28 (the Angelic Salutation), is so significant precisely because it represents the Incarnation – the act by which the Son of God became man.  As St. Louis De Montfort puts it, the Angelic Salutation (the Hail Mary) “has saved the world,” because by it (God becoming man in Mary’s womb) man had a chance to be saved.

“Blessed Alan De la Roche who was so deeply devoted to the Blessed Virgin had many revelations from her and we know that he confirmed the truth of these revelations by a solemn oath.  Three of them stand out with special emphasis: the first, that if people fail to say the Hail Mary (the Angelic Salutation which has saved the world) out of carelessness, or because they are lukewarm, or because they hate it, this is a sign that they will probably and indeed shortly be condemned to eternal punishment.  The second truth is that those who love this divine salutation bear the very special stamp of predestination. The third is that those to whom God has given the signal grace of loving Our Lady and of serving her out of love must take very great care to continue to love and serve her until the time when she shall have had them placed in heaven by her divine Son in the degree of glory which they have earned.”  (The Secret of the Rosary, p. 45.)

The Hail Mary, and Catholics’ petitions throughout history to the Mother of God, are prophesied by Our Lady herself in Luke 1:48: “…for behold from henceforth all generations shall call me blessed.” The Catholic commentary on this verse puts it well:

“These words [Luke 1:48] are a prediction of that honor which the Church in all ages should pay to the Blessed Virgin.  Let Protestants examine whether they are in any way concerned in this prophecy.” (Challoner)