Reference for Bava Kamma 76:6

צעירה דקאמרה בן עמי א"ל הקב"ה למשה (דברים ב, יט) וקרבת מול בני עמון אל תצורם ואל תתגר בם כלל דאפילו אנגריא לא תעביד בהו

At all times should a man try to be first in the performance of a good deed, as on account of the one night by which the elder [daughter]<span class="x" onmousemove="('comment',' V. p. 216, n. 6. ');">⁸</span> preceded the younger she preceded her by four generations [in having a descendant] in Israel: Obed, Jesse, David and Solomon.<span class="x" onmousemove="('comment',' Cf. Ruth IV, 13-22. ');">⁹</span>

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