'Pillar of Fire' in the Bible

Moreover in a pillar of cloud thou leddest them by day; and in a pillar of fire by night, to give them light in the way wherein they should go.

yet thou in thy manifold mercies forsookest them not in the wilderness: the pillar of cloud departed not from over them by day, to lead them in the way; neither the pillar of fire by night, to show them light, and the way wherein they should go.