Psalms 78:50

50.He made a way to his anger. (352) To take away all excuse from this ungrateful people, whom the most evident and striking proofs of the goodness of God which were presented before their eyes could not keep in their obedience to him, it is here again repeated that the wrath of God overflowed Egypt like an impetuous torrent. The miracle adverted to is the last which was there wrought, when God, by the powerful hand of his angel, slew, in one night, all the first-born of Egypt. According to a common and familiar mode of speaking in the Hebrew language, the first-born are called the beginning, or the first-fruits of strength. Although the old advance to death as they decline in years, yet as they are in a manner renewed in their offspring, and thus may be said to recover their decayed strength, the term strength is applied to their children. And the first-born are called the beginning or the first-fruits of this strength, as I have explained more at large on Genesis 49:3. The houses of Egypt are called the tents of Ham, because Misraim, who gave the name to the country, was the son of Ham, Genesis 10:6. Farther, there is here celebrated the free love of God towards the posterity of Shem, as manifested in his preferring them to all the children of Ham, although they were possessed of no intrinsic excellence which might render them worthy of such a distinction.