Nicene and Post-Nicene Fathers, Ser. II, Vol. XIV:
The Canons of the Synods of Sardica, Carthage, Constantinople, and Carthage Under St. Cyprian, Which Canons Were Received by the Council in Trullo and Ratified by II. Nice.: Canon XXXV

Canon XXXV.  (Greek xxxviii.)

That bishops or clergymen should not easily set free their sons.

That bishops or clerics should not easily let their children pass out of their power; unless they were secure of their morals and age, that their own sins may pertain to them.

Notes.

Ancient Epitome of Canon XXXV.

Bishops and clergy shall not set their children free until their morals are established.

This canon is Canon xiij. of the Synod of Hippo a.d. 393.