On the Catholic Priesthood
The confessor is forbidden under grave penalties ever to betray by word, sign, or in any other way, what he has heard in Sacramental confession. The obligation of the seal of confession differs from all other secrets, in that it is never lawful under any circumstances to make known the least thing that has been manifested by a penitent in confession. If questioned about confessional matter, even in a court of justice, the priest must always answer that he knows nothing about it, as with perfect truth he may do, for what he knows as a confessor he knows as the Vicegerent of God, not as man.
Not only the priest, but all others, who mediately or immediately come to know anything confessed to a priest with a view to absolution, are bound by the obligation of the seal. The obligation of the seal is imposed in favor of the penitent; it is the penitent's secret, but he himself is not bound by it. It does not follow, however, that penitents may without let or hindrance talk to others about what the confessor has said to them in the confessional. They are at least bound by a natural obligation to reveal nothing which would tend in any way to injure or aggrieve the confessor. The religious obligation of keeping secret anything that is manifested in Sacramental confession is imposed by the natural, the divine, and by positive ecclesiastical law.