Surah Ar-Rad, verse 17

أَنزَلَ مِنَ ٱلسَّمَآءِ مَآءً فَسَالَتْ أَوْدِيَةٌۢ بِقَدَرِهَا فَٱحْتَمَلَ ٱلسَّيْلُ زَبَدًا رَّابِيًا ۚ وَمِمَّا يُوقِدُونَ عَلَيْهِ فِى ٱلنَّارِ ٱبْتِغَآءَ حِلْيَةٍ أَوْ مَتَـٰعٍ زَبَدٌ مِّثْلُهُۥ ۚ كَذَٰلِكَ يَضْرِبُ ٱللَّهُ ٱلْحَقَّ وَٱلْبَـٰطِلَ ۚ فَأَمَّا ٱلزَّبَدُ فَيَذْهَبُ جُفَآءً ۖ وَأَمَّا مَا يَنفَعُ ٱلنَّاسَ فَيَمْكُثُ فِى ٱلْأَرْضِ ۚ كَذَٰلِكَ يَضْرِبُ ٱللَّهُ ٱلْأَمْثَالَ ﴿١٧﴾

13:17 He sends down rain from the sky, causing the valleys to flow, each according to its capacity, and the torrent carries along rising foam, similar to the slag produced from metal that people melt in the fire to make ornaments or tools. This is how Allah compares truth to falsehood: as for the residue, it is then cast away, but that which benefits people remains on the earth. This is how Allah sets forth comparisons