Albert Barnes on Acts 20:31

Therefore watch. Mt 24:42. In view of the dangers which beset yourselves, Acts 20:28, the danger from men not connected with the church, Acts 20:29, and the danger that shall arise from the lovers of power among yourselves, Acts 20:30, be on your guard. Observe the approach of danger, and set yourselves against it.

Remember. Recall my counsels and admonitions in reference to these dangers.

By the space of three years. In Acts 19:10, we are told that Paul spent two years in the school of Tyrannus. In Acts 19:8, it is said that he was teaching in the synagogue at Ephesus three months. In addition to this it is not improbable that he spent some months more in Ephesus in instructing the church in other places. Perhaps, however, by the phrase three years, he meant to use merely a round number, denoting about three years; or, in accordance with the Jewish customs, part of each of the three years-- one whole year, and a considerable portion of the two others. Mt 12:40.

I ceased not. I continued to do it.

To warn. To admonish; to place before the mind, νουθετων; setting the danger and duty of each individual before him.

Every one. He had thus set them an example of what he had enjoined, Acts 20:28. He had admonished each individual, whatever was his rank or standing. It is well when a minister can refer to his own example as an illustration of what he meant by his precepts.

Night and day. Continually; by every opportunity.

With tears. Expressive of his deep feeling and his deep interest in their welfare. Acts 20:19.

(e) "watch" 2Ti 4:5 (*) "warn" "admonish" (f) "every one" Col 1:28