John’s disciples: Most Jewish rabbis had students who learned from them and served them (see also Acts 19:1–7).
frequently fast and pray: Many devout Jews fasted two days a week (Luke 18:12). Fasting was associated with spiritual preparation and repentance (Esther 4:16; 2 Samuel 12:22; Joel 1:14; Jonah 3:5). Fasting is not a way to become righteous (to be made right with God; Isaiah 58:4–5; Jeremiah 14:12). But it is a spiritual pratice that helps a person become closer to God. Fasting is often connected to prayer and spiritual retreat.
but Yours keep on eating and drinking: The point was that they did not fast regularly.