Adam Clarke on Acts 13:25

As John fulfilled his course - As John was fulfilling his race, he said, etc. It has been supposed that the word δρομον, course, or race, is used here to point out the short duration of the Baptist's ministry, and the fervent zeal with which he performed it. It signifies properly his ministry, or life. A man's work, employment, function, etc., is his race, course, or way of life. John had a ministry from God; and he discharged the duties of it with zeal and diligence; bore the fatigues of it with patience and resignation; and was gloriously successful in it, because the hand of the Lord was with him.