Surah An-Najm (The Stars), Verse 28

وَمَا لَهُمْ بِهٖ مِنْ عِلْمٍ اِنْ یَّتَّبِعُوْنَ اِلَّا الظَّنَّ وَاِنَّ الظَّنَّ لَا یُغْنِیْ مِنَ الْحَقِّ شَیْـًٔا ۟

Wa maa lahum bihee min 'ilmin iny yattabi'oona illaz zanna wa innaz zanna laa yughnee minal haqqi shai'aa

“But they have no knowledge therein. They follow nothing but conjecture; and conjecture avails nothing against Truth.”

Quran 53:28 (Yusuf Ali Translation)