Sforno on Genesis 14:15/ספורנו על בראשית י״ד:ט״ו

1ויחלק עליהם לילה, he divided his forces all around them to make them believe that they were being attacked by large forces from several fronts. We have been told about a similar situation in Kings II 7,6 when the Aramites fled headlong after hearing noises that convinced them that they were being attacked by large forces.

2לילה, this was also part of the subterfuge, preventing the kings from realising that they were facing insignificant numbers of opponents. In Samuel II 17,1 this was the advice to Avshalom by Achitofel when he advised to pursue David at night.

3ויכם, the defeat caused them to flee.

4 וירדפם, the beginning of all pursuits is putting people to flight.