According to search-discovered classical Islamic scholarship, the concepts of 'Slag' (Khabath) and 'Foam/Dross' (Zabad) are central to a profound parable in the Quran (13:17) that illustrates the fundamental nature of truth versus falsehood. Tafsir authorities like Ibn Kathir and Al-Tabari explain this verse uses two analogies: the transient foam carried on a flood and the worthless dross that rises when smelting metals. Both the foam and the slag symbolize falsehood (Al-Batil)—be it disbelief, doubt, or empty deeds—which may appear prominent and swelling but is ultimately cast off and vanishes. In stark contrast, that which is beneficial and pure—like the water and the refined metal—remains on the earth to benefit humanity. This powerful imagery establishes a divine principle: truth is enduring, beneficial, and substantive, while falsehood, despite its outward appearance, is ephemeral and devoid of value.