Ar-Ra'd 13:17

Anzala mina assama-i maanfasalat awdiyatun biqadariha fahtamalaassaylu zabadan rabiyan wamimma yooqidoonaAAalayhi fee annari ibtighaa hilyatinaw mataAAin zabadun mithluhu kathalika yadribuAllahu alhaqqa walbatila faammaazzabadu fayathhabu jufaan waamma mayanfaAAu annasa fayamkuthu fee al-ardi kathalikayadribu Allahu al-amthal

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.

He sent down water from the heavens, so the canals flowed according to their capacity, and the flood carried bulging scum. And a similar scum comes up from what they melt in the fire to obtain ornaments or other objects. This is how Allah depicts the truth and the untruth. As for the scum, it goes to be thrown away, while that which benefits people remains on the earth. This is how Allah brings out the parables.