Charles Ellicott Commentary 1 Chronicles 19:9

"And the children of Ammon came out, and put the battle in array at the gate of the city: and the kings that were come were by themselves in the field." — 1 Chronicles 19:9 (ASV)

Before the gate of the city. —Literally, in the outlet of the city. Samuel has in the outlet of the gate. The city appears to have been Medeba (1 Chronicles 19:7).

And the kings that were come. —Samuel repeats the names: And Aram-zobah and Rehob, and the men of Tôb and Maachah.

Were. —Rather, arrayed for battle (to be supplied from the former sentence).

In the field. —In the open country, or plain (mîshôr) of Medeba (Joshua 13:9; Joshua 13:16), where there was room for the movements of cavalry and chariots.