Tradition
St. Benedict of Nursia
The Rule of St. Benedict
Chapter XXVI. Of Those Who Without the Command of the Abbot Associate With the Excommunicated
CHAPTER XXVI
Of Those Who without the Command of the Abbot Associate with the Excommunicated
If any brother presume to associate with an excommunicated brother in any way, or to speak with him, or to send him a message, without the command of the Abbot, let him incur the same penalty of excommunication.
Source: The Rule of St. Benedict (CCEL)