As they ministered to the Lord,.... That is, the five prophets and teachers before mentioned; and whose ministry lay in preaching the Gospel, teaching the people the doctrines of it, and expounding prophecies, and also in prayer; to which latter the Syriac version restrains their ministry, rendering it, "as they prayed to God"; but the phrase seems to be more extensive: "and fasted"; which the Jews were much used to, and the believing ones had not yet left it off; their custom was to fast on Mondays and Thursdays: See Gill on "Lu 18:12".
Whether it was on one of those days, that these men were ministering and fasting, is not certain; but this we may be sure of, it was not on the Jewish sabbath, for on that day they never fasted; very likely that this was a fast appointed and fixed among themselves, on some particular occasion; it may be on account of the famine, which was at this time, Ac 11:28.