New Defender's Study Bible Notes
4:8 drew off his shoe. This act symbolized the fact that he was no longer able to walk on the tract of land under discussion and was giving up his right as kinsman to claim it for himself.
4:18 Pharez. Pharez was the son of Judah, so this genealogical summary clearly shows that David is descended from Judah, and thus able to fulfill Jacob’s prophecy (Genesis 49:10) of the sceptre.
4:20 Salmon. According to Matthew 1:5, Salmon married Rahab the converted harlot, sometime after the fall of Jericho, and therefore Boaz was their son. (See introductory notes concerning gaps that may have occurred between Salmon and Boaz.)
4:22 David. David was evidently born near the end of the judges period and Salmon near the beginning. The four generations between Salmon and David thus seem to have spanned the entire period “when the judges ruled” (Ruth 1:1), although it is possible that there are gaps in this genealogy. Note also that ten names are listed in the genealogy from Pharez to David. Deuteronomy 23:2 says that an illegitimate son could “not enter into the congregation of the Lord” until “the tenth generation.” Pharez, of course, was the illegitimate son of Judah and Tamar, but this genealogy indicates that David was free from this exclusion, even if there are no gaps in the genealogy.