Blood, the Last Sign

So Allah (swt) then sent upon them al-dam: blood. Allah knows best what exactly the punishment of blood was, but some of the mufassirūn say that the people of Firʿawn — the people of Egypt — would go and take water from the Nile, and by the time they reached home, it was thick blood. They would take water out of their wells, and by the time they wanted to drink it, it was thick blood. Banū Isrāʾīl would take water from the Nile and drink it as water; they would take water from the wells, and it would be water. But with the Egyptians, the people of Firʿawn, it would turn into blood. What could they do? They needed to drink.

They went to Mūsā and said: release us from this punishment. Allah (swt) released them from this punishment — but that was the last sign they would receive. Allah (swt) gave them enough chances. They committed their kufr with insistence; they had seen all of the signs, and they still remained in their kufr of Allah (swt).