Eliyahu Prays for Rain

What does this episode of Eliyahu's prayer for rain add to the wider story? The storyline before and after Eliyahu's prayer appears to be stalled at the same point: Eliyahu encouraging Achav to proceed to Yizra'el hastily because the rain is on its way.  Classic commentators suggest that an immediate rain was necessary to impress Ahav or to make the clear connection between the sin of idolatry and the drought. However, there might be an additional lesson for Eliyahu himself. Though he decreed the drought, ultimately it is by God's word that the rain will come or go.