Reference for Avodah Zarah 106:5

אם עתידין לחזור כמלחמת יהושע אינה בטילה מידי מלחמת יהושע מיהדר הדור ה"ק אם עתידין לחזור הרי הוא כמלחמת יהושע ואין לה בטילה

“If with the intention of returning [to claim the idol] as happened during the war waged by Joshua, it is not annulled!” But in the instance of the war waged by Joshua did they return? This is what it means: If [the owners] have the intention of returning, it is analogous to the war waged by Joshua and there can be no annulment.

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