Commentaries:
Jesus says that exhortations to "watch" apply to everyone (Mark 13:35-37). In this case, the parable that follows shows that the apostles have a special responsibility. In it, the steward in charge of the servants is a servant himself, teaching the importance of faithfulness in doing the will of the master (I Corinthians 4:2). Not only does Jesus teach the certainty of His return at an unexpected moment, but he also implies that the church - His disciples - would continue serving God for an unspecified time until His return. As He says, "Blessed is the servant whom His Lord will find so doing when He comes."
Martin G. Collins
Parable of the Faithful and Evil Servants