There shall be a great cry throughout all the land of Egypt, such as there has never been, nor ever will be again.
Warning is here given to Pharaoh of the last and conquering plague which was now to be inflicted. This was the death of all the first-born in Egypt at once, which had been first threatened (Exo 4:23, I will slay thy son, thy first-born), but is last executed; less judgments were tried, which, if they had done the work would have prevented this.
Commenting on Exodus 11:4-10
And there shall be a great cry throughout all the land of Egypt,.... Of parents for the loss of their firstborn sons, their heirs, the support and glory of their families; children for the loss of their elder brethren; and servants for the loss of the prime and principal in their masters' houses; and all in a dreadful fright, expecting instantly death themselves: such as...
shall be a great cry throughout all the land--In the case of a death, people in the East set up loud wailings, and imagination may conceive what "a great cry" would be raised when death would invade every family in the kingdom.