a) The faithful who on the last Sunday but one of October,
or some other appointed by the local Ordinary, according to
the regulations of the Rescript of the Sacred Congregation
of Rites, April 14, 1926, take part in one of the sacred
functions usually celebrated for the Missions, and offer their
devout prayers for the conversion of pagans, may gain: An
indulgence of 7 years. Those, moreover, who make their
confession, receive Holy Communion, and pray as above,
may gain: A plenary indulgence.
b) The faithful in places where a Missionary Day is not
observed, who on the last Sunday but one in October, visit
some church or public oratory and pray for the conversion
of pagans, may gain: An indulgence of 7 years. A plenary
indulgence, if moreover they make their confession and received Holy
Communion.

Raccolta #612 Prayer
O God, the everlasting Creator of all things, remember that
the souls of unbelievers were made by Thee and formed in
Thine own image and likeness. Remember that Jesus, Thy
Son, endured a most bitter death for their salvation. Permit
not, I beseech Thee, O Lord, that Thy Son should be any
longer despised by unbelievers, but do Thou graciously
accept the prayers of holy men and of the Church, the
Spouse of Thy most holy Son, and be mindful of Thy
mercy. Forget their idolatry and unbelief, and grant that
they too may someday know Him whom Thou hast sent,
even the Lord Jesus Christ, who is our Salvation, our life
and Resurrection, by whom we have been saved and
delivered, to whom be glory for endless ages. Amen.
An indulgence of 500 days. A plenary indulgence on the usual
conditions, if the prayer is devoutly recited daily for a month.