Commentaire sur La Genèse 14:15

ויחלק עליהם AND HE DIVIDED HIMSELF AGAINST THEM — In accordance with its plain sense you must invert the order of the words of the verse: “And he divided himself, he and his servants, against them, at night”, as is the manner of those who pursue their enemies — they divide themselves up to follow after those of whom they are in pursuit when these flee in different directions.

AND HE DIVIDED HIMSELF, BY NIGHT. Rashi wrote: “In accordance with the plain sense of the verse it means [that they divided into groups] as is the manner of those who pursue their enemies when they flee in different directions. By night means that even after it became dark, they did not cease pursuing them.”
The correct interpretation is that he pursued the enemies to Dan during the daytime with his entire army. When it became dark and he was not able to see by which road they fled, he divided his people and servants into two or three groups, taking one part with him, and they pursued them on all roads, smiting them as far as Hobah, which is on the left hand of Damascus. Then he returned from pursuing them. The order of the words [in the verse are thus interpreted as follows]: “And he divided himself, he and his servants, by night.”

ויחלק 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.