﴿ أَنزَلَ مِنَ ٱلسَّمَآءِ مَآءًۭ فَسَالَتْ أَوْدِيَةٌۢ بِقَدَرِهَا فَٱحْتَمَلَ ٱلسَّيْلُ زَبَدًۭا رَّابِيًۭا ۚ وَمِمَّا يُوقِدُونَ عَلَيْهِ فِى ٱلنَّارِ ٱبْتِغَآءَ حِلْيَةٍ أَوْ مَتَٰعٍۢ زَبَدٌۭ مِّثْلُهُۥ ۚ كَذَٰلِكَ يَضْرِبُ ٱللَّهُ ٱلْحَقَّ وَٱلْبَٰطِلَ ۚ فَأَمَّا ٱلزَّبَدُ فَيَذْهَبُ جُفَآءًۭ ۖ وَأَمَّا مَا يَنفَعُ ٱلنَّاسَ فَيَمْكُثُ فِى ٱلْأَرْضِ ۚ كَذَٰلِكَ يَضْرِبُ ٱللَّهُ ٱلْأَمْثَالَ ﴾

“[Whenever] He sends down water from the sky, and [once-dry] river-beds are running high according to their measure, the stream carries scum on its surface; and, likewise, from that [metal] which they smelt in the fire in order to make ornaments or utensils, [there rises] scum. In this way does God set forth the parable of truth and falsehood: for, as far as the scum is concerned, it passes away as [does all] dross; but that which is of benefit to man abides on earth. In this way does God set forth the parables”

Commentary The outcome of both parables is that foam does appear prominent for a while on the real thing, but it finally gets to be thrown away and the real thing remains. Similar is the case of the false. Though the false may, for a short while, appear to have overcome the true, but the false is finally subdued and eliminated and that which is true remains and stands manifestly proven. (Tafsir A1-Jalalayn)