Abigail was the mother of Amasa, whose father was Jether the Ishmaelite.
References for 1 Chronicles 2:17
Caleb son of Hezron had children by his wife Azubah (and by Jerioth). These were her sons: Jesher, Shobab and Ardon.
References for 1 Chronicles 2:18
When Azubah died, Caleb married Ephrath, who bore him Hur.
References for 1 Chronicles 2:19
Hur was the father of Uri, and Uri the father of Bezalel.
References for 1 Chronicles 2:20
Later, Hezron, when he was sixty years old, married the daughter of Makir the father of Gilead. He made love to her, and she bore him Segub.
References for 1 Chronicles 2:21
Segub was the father of Jair, who controlled twenty-three towns in Gilead.
(But Geshur and Aram captured Havvoth Jair, as well as Kenath with its surrounding settlements—sixty towns.) All these were descendants of Makir the father of Gilead.
References for 1 Chronicles 2:23
After Hezron died in Caleb Ephrathah, Abijah the wife of Hezron bore him Ashhur the father of Tekoa.
References for 1 Chronicles 2:24
The sons of Jerahmeel the firstborn of Hezron: Ram his firstborn, Bunah, Oren, Ozem and Ahijah.
References for 1 Chronicles 2:25
Jerahmeel had another wife, whose name was Atarah; she was the mother of Onam.
The sons of Ram the firstborn of Jerahmeel: Maaz, Jamin and Eker.