9 If evils increase, the devotion of the People of God should also increase. And so, venerable brothers, We want you to take the lead in urging and encouraging people to pray ardently to our most merciful mother Mary by saying the Rosary during the month of October, as We have already indicated. This prayer is well-suited to the devotion of the People of God, most pleasing to the Mother of God and most effective in gaining heaven's blessings. The Second Vatican Council recommended use of the Rosary to all the sons of the Church, not in express words but in unmistakable fashion in this phrase: "Let them value highly the pious practices and exercises directed to the Blessed Virgin and approved over the centuries by the magisterium." (9)
Source: Christi Matri (Vatican.va)