“‘See!

The day is coming,

Burning

Like an oven.

All the arrogant

Will be stubble.

All evildoers

Will be stubble.

The day that comes

Shall burn them up.’

Says Yahweh of hosts.

Thus,

It will leave them

Neither root

Nor branch.”

The day of Yahweh would be a fiery hot day.  The wicked ones would burn up as if they were in an oven.  All the arrogant and evildoers would be like stubble for the fire that would burn all of them up.  Yahweh of hosts was going to leave these wicked people without roots or branches.  Thus, the idea that God will come with fire has its biblical origins here.