Lice

So Allah (swt) sent another sign upon them, and that is al-qummal: lice, or ticks. Allah sent lice and ticks upon them — these insects that bite your body and suck the blood. Allah (swt) sent these insects upon them in millions — millions. The insides of their clothes would be filled with lice and ticks. When they went to their beds, the beds would be lined with lice and ticks. Wherever they went, in their houses, these ticks were flying around the houses and over their bodies. Their life became terrible and miserable. They could not stand it.

And who can release them from that? Allah. They went to Mūsā. Mūsā made duʿāʾ. Allah (swt) took the punishment away — fa-idhā hum yankuthūn — and they broke their promise again. Subḥān Allāh, look at the insistence on kufr.