ZERUIAH (zêr'ū-ī'a, Heb. tserûyâh). Sister of David and mother of Joab, Abishai, and Asahel. She was probably not a daughter of Jesse, but a daughter of David’s mother by an earlier marriage with Nahash (2Sam.17.25).
ZERUIAH zĭ rōō’ yə (צְרוּיָ֣ה; LXX, Ζαρουία). Zeruiah was the mother of Abisha, Joab, and Asahel who were chief officers in David’s kingdom. She is identified as David’s sister (1 Chron 2:16), but she could have been a stepsister, the daughter of Jesse’s wife by a former marriage to Nahash (2 Sam 17:25).
Although Zeruiah is mentioned at least twenty-five times in the historical records of Samuel, Kings, and Chronicles no mention is made of her husband. The fact that Joab, who served as David’s commander of the army, and his brothers are repeatedly identified as sons of Zeruiah makes it apparent that she was a well-known individual. Although numerous explanations have been given concerning the Scripture’s silence in identifying Zeruiah’s husband—he may have died young, he may have been a foreigner and she retained her identity with her clan, he may have been rather insignificant and obscured by her personality, or the writer may have followed the custom of tracing kinship through the female line—the fact remains that she must have been well known and recognized to be repeatedly identified as the mother of Joab, the general of David’s army.
International Standard Bible Encyclopedia (1915)