Verse 21. Slew - This history is not recorded else where in scripture, but it is in the ancient Hebrew writers. The Philistines (one of whose cities Gath was) and the Egyptians were next neighbours; and in those ancient times it was usual for such to make inroads one into another's country, and to carry thence what prey they could take. And as the Philistines had probably made such inroads formerly into Egypt, and particularly into the land of Goshen, which was the utmost part of Egypt bordering upon the Philistines land; so the Israelites might requite them in the like kind: and particularly the children of Ephraim, to their own loss. And this seems to have happened a little before the Egyptian persecution, and before the reign of that new king mentioned Exod. i, 8. And this clause, that were born in that land, may be added emphatically, as the motive which made them more resolute in their fight with the Ephraimites, because they fought in, and for their own land, wherein all their wealth and concerns lay.
Verse 23. Bare a son - Thus the breach was in some measure repaired, by the addition of another son in his old age. When God thus restores comfort to his mourners, he makes glad according to the days wherein he afflicted, setting the mercies over against the crosses, we ought to observe the kindness of his providence. Yet the joy that a man was born into his family could not make him forget his grief. For he gives a melancholy name to his son, Beriah, that is, in trouble: for he was born when the family was in mourning. It is good to have in remembrance the affliction and the misery which are past, that our souls may be humbled within us.