He sendeth down water from the heaven, so that the valleys flow according to their measure; then the torrent beareth the scum on top, and from that over which they kindle a fire seeking ornament or goods- ariseth a scum like thereto: Thus doth Allah propound the truth and falsity. Then as for the scum, it departeth as rubbish, and as for that which benefiteth the mankind, it lasteth on the earth: Thus doth Allah propound the similitudes.