תלמוד בבלי, מסכת ברכות דף לט עמוד ב
רבי אמי ורבי אסי כי מיקלע להו ריפתא דעירובא - שרו עילויה, אמרי: הואיל ואיתעביד בה חדא מצוה - ליתעביד בה מצוה אחרינא
When Rav Ammi and Rav Assi happened to get hold of a loaf which had been used for an eruv, they used to say over it the blessing, 'who bringest forth bread from the earth'[ and eat it], saying, Since one religious duty has been performed with it, let us perform with it still another. [Translation by Soncino Press]
Suggested Discussion Questions:
What can this source teach us about sustainable resource use?
Time Period: Rabbinic (Maccabees through the Talmud)