He sends down from the sky, rain, and valleys flow according to their capacity, and the torrent carries a rising foam. And from that [ore] which they heat in the fire, desiring adornments and utensils, is a foam like it. Thus Allāh presents [the example of] truth and falsehood. As for the foam, it vanishes, [being] cast off; but as for that which benefits the people, it remains on the earth. Thus does Allāh present examples.
Allah strikes an example of the erosion of falsehood and the survival of truth with rainwater that comes down from the sky and causes riverbeds to flow, each according to its size, whether big or small. The overflowing water carries on its surface scum and froth that rise above the water. He then gives another example of falsehood and truth with some of the metals that people put into a furnace in order to melt down and to make ornaments for people. Falsehood is like the scum and froth that floats above the water and like the slag expelled by smelting the metal. Truth is like the pure water that can be drunk and that causes fruits, grass and vegetation to grow; and like the metal that remains after smelting, which is of benefit to people. Just as Allah has given these two examples, He gives many examples to people so that truth may be distinguished from falsehood.