In ancient Israel, it was customary for a remarried widow to name the first son she had with her new husband after her dead husband. In fact, God’s law required it. In order to maintain Mahlon’s name in his family, his widow (Ruth) and her new husband (Boaz) should have named their son after Mahlon.
And that’s what Boaz said he was going to do. He even said that was the reason he was marrying Ruth, so the dead man’s name would be maintained and wouldn’t disappear.
But apparently that’s not what they actually did. Boaz and Ruth named their first son Obed, not Mahlon.
- Maybe Boaz lied.
- Maybe Boaz changed his mind.
- Maybe Boaz named their first son Obed, and then waited until they had another son before he got around to having a son named Mahlon (and the writers of the Bible didn’t think that son was worth mentioning). Even though having a son named Mahlon was the reason he married Ruth in the first place. And even though the law says you have to give the dead husband’s name to the first son.