Canon 15
About the prohibition for lay people who do not belong to the clergy as singers to stand on the pulpit and sing without permission.
About what should not be sung in church by anyone other than the clergy singers who ascend to the pulpit and sing according to diphthera (ἀπό διφθέρας).
Greek original
Περὶ τοῦ μὴ δεῖν πλὴν τῶν κανονικῶν ψαλτῶν, τῶν ἐπὶ τὸν ἄμβωνα ἀναβαινόντων, καὶ ἀπὸ διφθέρας ψαλλόντων, ἑτέρους τινὰς ψάλλειν ἐν ἐκκλησίᾳ.
Parallel canons
Ап.26IВс.16Трул.43375VIIВс.14Лаод.59Карф.103