Ezekiel 20:9

But I wrought for My name's sake, He refrained from executing His wrath for the sake of His own honor, that it should not be polluted before the heathen, who would have taken occasion to blaspheme if Israel had been severely punished by the Lord at that time, while the Egyptians were witnesses, among whom they were, in whose sight I made Myself known unto them, as by the ten great plagues, in bringing them forth out of the land of Egypt. That was the first stage of Israel's national existence, or rather the preparation for this stage. Even in those days the children of Israel had been so stubborn and willful that the Lord felt constrained to punish them severely, and only His great mercy had saved them from the well-merited punishment.