2 Thessalonians 2:15

15Soἄραthenοὖν,brothersἀδελφοί,stand firmστήκετε,andκαὶhold fastκρατεῖτεto theτὰςtraditionsπαραδόσειςthatἃςyou were taughtἐδιδάχθητεwhetherεἴτεbyδιὰwordλόγουorεἴτεbyδι’letterἐπιστολῆςfrom usἡμῶν.

So then, brothers, stand firm and hold fast to the traditions that you⁺ were taught, whether by word or by letter from us.