'Pillar of Fire' in the Bible

And you went before them by day in a pillar of cloud, and in a pillar of fire by night, to give them light on the way they were to go.

Even then, in your great mercy, you did not give them up in the waste land: the pillar of cloud still went before them by day, guiding them on their way, and the pillar of fire by night, to give them light, and make clear the way they were to go.