Wa Kala Mousa Yarabih, Allah Subhanahu Wa Ta'ala

Musa alayhi salam to this point had not made the du'a against viram yet. All his du'as were yah Allah, these people are now suffering, take it away from them. So it was actually a mercy. This is why sometimes when there are non-muslims around and we go to assist, it should be a means of dawah in the sense that we should be thinking within ourselves "Yah Allah guide this person"