In the second chapter we have to do with the sons of Jacob, here spoken of in the later name Israel, applied in the grace of God. Of them all, Judah the fourth, is presented first to lead our thoughts to David and the royal family of Israel, objects of the favor of God, in whom was to be displayed the sovereignty of that free, unmerited favor, and as to whom promises were given that could only, because of man's utter failure, be fulfilled in that Son of David who is Son of God, Christ the Lord. Chapters 2 and 3, and chapter 4 down to verse 24, are concerned with the family of Judah.
Er, firstborn of Judah, was evil in the sight of the Lord, and He slew him (verse 3); sin meets retribution, not always at man's hand, but certainly at God's. And there was a troubler of Israel among Judah's descendants who transgressed, and met swift judgment (verse 7, and Joshua 7). The free electing grace of God is further shown in David's being the seventh and youngest of his family, the least in his father's house (verse 15).