Canon 20
About the fact that it is not appropriate for a deacon to sit in the presence of an elder without his command. Likewise for the clerics with the subdeacons in the presence of the deacon.
That a deacon should not sit down before the presbyter, but can sit after the presbyter’s command. Deacons receive the same honor from ministers and all clergy.
Greek original
Ὅτι οὐ δεῖ διάκονον ἔμπροσθεν πρεσβυτέρου καθέζεσθαι, ἀλλὰ μετὰ κελεύσεως τοῦ πρεσβυτέρου καθέζεσθαι. Ὁμοίως δὲ ἔχειν τιμὴν καὶ τοὺς διακόνους ὑπὸ τῶν ὑπηρετῶν καὶ πάντων τῶν κληρικῶν.
Parallel canons
Ап.1539IВс.1518Трул.716Антиох.5