Salmon begat Boaz - Matthew has preserved the additional interesting information that the mother of Boaz was Rahab Josh. 2; 6. It is possible that the circumstance that the mother of Boaz was a Canaanite may have made him less indisposed to marry Ruth the Moabitess. As regards the whole genealogy in Ruth 4:18-22, it should be remarked that it occurs four times in Scripture, namely, here, 1-Chronicles 2:10-12; Matthew 1:3-6; and Luke 3:32-33, and is of course of singular importance as being the genealogy of our Lord. One or two difficulties in it still remain unsolved.

And Salmon begat Boaz - The Targum goes on, "And Salmon begat Absan the judge; he is Boaz the Just, on account of whose righteousness the people of the house of Israel were redeemed from the hands of their enemies; and at whose supplication the famine departed from the land of Israel."
And Boaz begat Obed - "Who served the Lord in this world with a perfect heart."

And Salmon begat Boaz,.... Of Rahab the harlot, whom he married, Matthew 1:5 the very same person that makes a principal part of this book, and whom the Targum here takes to be the judge Ibzan; see Gill on Ruth 1:1.
and Boaz begat Obed; of Ruth; of whom see the preceding verses.