New Defender's Study Bible Notes
3:13 Zenas. “Zenas” is not mentioned otherwise. His Greek name suggests that he was a Greek lawyer, rather than Jewish. Apollos is mentioned a number of times elsewhere (e.g., Acts 18:24).
3:13 on their journey diligently. Evidently Apollos and Zenas had been assisting Titus in Greece, and Paul was now sending Artemas and Tychicus to replace them while they went on to minister elsewhere. Titus himself was going to be needed by Paul at Nicopolis.