Reference for Bava Batra 231:13

ויואב לא הניח בן והכתיב (עזרא ח, ט) מבני יואב עובדיה בן יחיאל אלא דוד שהניח בן כמותו נאמרה בו שכיבה יואב שלא הניח בן כמותו נאמרה בו מיתה

why was [the expression of] 'sleeping' used in the case of David, and [that of] 'death' in the case of Joab? 'Sleeping' was used in the case of David because he left a son; 'Death' was used in the case of Joab because he left no son. Did not Joab leave a son? Surely, it is written, Of the sons of Joab, Obadiah the son of Jehiel!<span class="x" onmousemove="('comment',' Ezra VIII, 9. ');">²¹</span> — But, [this is the reply,] with David who left a son like himself [the expression of] 'sleeping' was used; with Joab who did not leave a son like himself, 'death' was used.

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