'Pillar of Fire' in the Bible

And You led them in the day by a cloudy pillar, and in the night by a pillar of fire, to give them light in the way in which they should go.

yet You in Your great mercies did not forsake them in the wilderness. The pillar of the cloud did not depart from them by day to lead them in the way, nor the pillar of fire by night, to show them light and the way in which they should go.