20 Before We conclude this Encyclical We also wish to ask you, Venerable Brethren, to recite Mary's rosary through the month of October with particular devotion, and to entreat the Virgin Mother of God in suppliant prayer, for another intention which is dear to Our heart: that the Roman Synod may bring many blessings and benefits upon this city; that the forthcoming Ecumenical Council, in which you will participate by your presence and your advice, will add wondrous growth to the universal Church; and that the renewed vigor of all the Christian virtues which We hope this Council will produce will also serve as an invitation and incentive to reunion for Our Brethren and children who are separated from this Apostolic See.
Source: Grata Recordatio (Vatican.va)