Therefore watch... — The word was, as it were, an echo from our Lord’s teaching (Matthew 24:42; Matthew 25:13, et al.), which could hardly have been unknown to St. Paul. Here, however, it receives a fresh significance from its connection with the term episcopi. They who were the bishops, the overseers, the watchers of the flock, ought, above all others, to set an example of vigilance.
By the space of three years. — Strictly speaking, the narrative of the Acts accounts for three months’ preaching in the synagogue (Acts 19:8), two years in the school of Tyrannus (Acts 19:10), and an undefined period embracing the time immediately before and after the tumult of Demetrius. This would be enough to warrant him describing the time of his ministry, speaking roughly, as extending over three years.
To warn every one night and day with tears. — Comp. Note on Acts 20:19.