John Gill Commentary 1 Chronicles 2:42

"And the sons of Caleb the brother of Jerahmeel were Mesha his first-born, who was the father of Ziph; and the sons of Mareshah the father of Hebron." — 1 Chronicles 2:42 (ASV)

Now the sons of Caleb the brother of Jerahmeel Called Chelubai, (1 Chronicles 2:9) and is the same Caleb spoken of in (1 Chronicles 2:18) and his sons next reckoned were by a third wife, Azubah, Ephrath being dead, (1 Chronicles 2:19) and these sons were

Mesha his firstborn, which was the father of Ziph; who gave name to the city of Ziph; there were two of this name in the tribe of Judah, (Joshua 15:24Joshua 15:55) or this is the title of Mesha, governor of the city of Ziph; so the Targum calls him, prince of the Ziphites:

and the sons of Mareshah the father of Hebron; according to Kimchi and Ben Melech, the words are to be supplied thus, "and the sons of Ziph were Mareshah the father of Hebron"; which, though sometimes the name of a city in the tribe of Judah, is here the name of a man, from whom, perhaps, the city had its name, since Hebron is said to have sons in the next verse; Jarchi makes Mesha to be the prince of Ziph, and prince of the children of Mareshah, and prince of Hebron.