Council of Trent: Session XXV, Regulars and Nuns, Chapter X

CHAPTER X. Nuns shall confess and communicate once a month; an extraordinary Confessor shall be assigned them by the Bishop. The Eucharist shall not be reserved within the enclosure of the Convent.

Bishops and other Superiors of convents of nuns, shall take particular care that the nuns be admonished, in their constitutions, to confess their sins, and to receive the most holy Eucharist, at least once a month, that so they may fortify themselves, by that salutary safeguard, resolutely to overcome all the assaults of the devil. But besides the ordinary confessor, the bishop and other superiors shall, twice or thrice a year, offer them an extraordinary one, whose duty it shall be to hear the confessions of all the nuns. But that the most holy body of Christ be kept within the choir, or the enclosure of the convent, and not in the public church, the holy Synod forbids it; any privilege or indult whatsoever notwithstanding.

Translation: J. Waterworth, The Canons and Decrees of the Council of Trent (1848), Hanover Historical Texts Project transcription (1995).