Church Fathers on 2 Timothy 1:13

Not by letters alone did Paul instruct his disciple in his duty, but before by words also which he shows, both in many other passages, as where he says, “whether by word or our Epistle” 2 Thessalonians 2:15, and especially here. Let us not therefore suppose that anything relating to doctrine was spoken imperfectly. For many things he delivered to him without writing. Of these therefore he reminds him, when he says, “Hold fast the form of sound words, which you have heard of…