John Gill Commentary Nehemiah 9:12

"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." — Nehemiah 9:12 (ASV)

Moreover, you led them in the day by a cloudy pillar ,
&c.] The Israelites, to shelter them from the heat of the sun in a dry and barren wilderness:

and in the night by a pillar of fire, to give them light in the way
in which they should go ;
through a trackless desert, see (Exodus 13:21Exodus 13:22) .