Правило 10
On the prohibition for Orthodox Christians to marry heretics.
That members of the Church should not indiscriminately marry their children with heretics.
Greek original
Περὶ τοῦ μὴ δεῖν τοὺς τῆς ἐκκλησίας ἀδιαφόρως πρὸς γάμου κοινωνίαν συνάπτειν τὰ ἑαυτῶν παιδία αἱρετικοῖς.
Parallel canons
Ап.264565IVВс.14Трул.672Лаод.31Карф.21