Jamieson, Fausset and Brown on 1 Kings 18:4

4. an hundred prophets--not men endowed with the extraordinary gifts of the prophetic office, but who were devoted to the service of God, preaching, praying, praising, &c. (1Sa 10:10-12).

fed them with bread and water--These articles are often used to include sustenance of any kind. As this succor must have been given them at the hazard, not only of his place, but his life, it was a strong proof of his attachment to the true religion.