דברי הימים א ה:כ פירוש: רש״י

And they were assisted against them for the Lord helped them.

and the Hagarites and all who were with them other nations [that came] to their aid.

and He accepted their prayers וְנַעְתּוֹר, similar to if וַיֵּעָתֵר לוֹ accepted his prayer (Gen. 25:21).