Charles H. Spurgeon on Psalms 105:36

Are smote also all the firstborn in their land, the chief of all their strength. Now came the master blow. The Lord spoke before, but now he smites; before he only smote vines, but now he strikes men themselves. The glory of the household dies in a single night, the prime and pick of the nation are cut off, the flower of the troops, the heirs of the rich, and the hopes of the poor all die at midnight. Now the target was struck in the centre, there was no confronting this plague. Pharaoh feels it as much as the woman slave at the mill: he had smitten Israel, the Lord's firstborn, and the Lord repaid him to his face. What a cry went up throughout the land of Egypt when every house wailed its firstborn at the dead of night! O Jehovah, thou didst triumph in that hour, and with an outstretched arm didst thou deliver thy people.