( وَلَمَّا وَقَعَ عَلَيْهِمُ الرِّجْزُ ) (And when the punishment descended upon them): This punishment refers to horrifying things and torments that afflicted them.

( قَالُوا يَا مُوسَى ادْعُ لَنَا رَبَّكَ) (they said, “O Moses, invoke for us your Lord): Evidently, they believed that Prophet Moses (PBUH) was sent by a Lord (swt) who was not Pharao. They made him (PBUH) a promise that if he lifts up the punishment from them, then they would believe in what he (PBUH) was sent with.

( وَلَنُرْسِلَنَّ مَعَكَ بَنِي إِسْرَائِيلَ ) (and we will send with you the Children of Israel): They also promised that they would allow the Children of Israel to go with Prophet Moses (PBUH).