He sends down water from the clouds, then watercourses flow according to their measure, and the torrent bears along the swelling foam. And from that which they melt in the fire for the sake of making ornaments or apparatus arises a scum like it. Thus does Allah compare truth and falsehood. Then as for the scum, it passes away as a worthless thing; and as for that which does good to men, it tarries in the earth. Thus does Allah set forth parables.