The Council of Ephesus (431 AD)

If any have been condemned for evil practices by the holy Synod, or by their own bishops; and if, with his usual lack of discrimination, Nestorius (or his followers) has attempted, or shall hereafter attempt, uncanonically to restore such persons to communion and to their former rank, we have declared that they shall not be profited thereby, but shall remain deposed nevertheless.

Ancient Epitome of Canon V.

If one condemned by his bishop is received by Nestorius it shall profit him nothing.

This canon is interesting as shewing that thus early in the history of the Church, it was not unusual for those disciplined for their faults in one communion to go to another and there be welcomed and restored, to the overthrow of discipline and to the lowering of the moral sense of the people to whom they minister.