Acts 14:21

μαθητεύσαντες ἱκανούς, and having made many disciples. According to Christ’s words (Matthew 28:19), μαθητεύσατε πάντα τὰ ἔθνη. Of course teaching was a part of the process, but μαθητεύειν implies a stage beyond that. Perhaps ‘Gains of Derbe,’ whom St Luke mentions as one of Paul’s companions in a subsequent journey (Acts 20:4), may have been one of these. This is the more probable because he is there mentioned in the same clause with Timothy, who undoubtedly was converted by St Paul during this visit to Lycaonia.

ὑπέστρεψαν, they returned. Thus going back over the ground which they had travelled before, that they might provide for the spread of that seed of the word which they had imperilled themselves so greatly to sow.