Canon LIX.
Canons of Local Councils Received in Trullo (Sardica, Carthage) · The Seven Holy Ecumenical Councils
That clerics be not compelled to give testimony in public concerning the cognizance of their own judgment.
LocalT 2.63.2
It should be petitioned also that they deign to decree, that if perchance any shall have been willing to plead their cause in any church according to the Apostolic law imposed upon the Churches, and it happens that the decision of the clergy does not satisfy one of the parties, it be not lawful to summon that clergyman who had been cognitor or present, into judgment as a witness, and that no person attached to any ecclesiastic be compelled to give testimony.
LocalT 2.63.3
A cleric who has decided a case shall not, if it be displeasing, be summoned to a tribunal to give evidence concerning it; and no ecclesiastical person shall be forced to give testimony.
LocalT 2.63.6