Surah An-Nur (The Light), Verse 16

وَلَوْلَاۤ اِذْ سَمِعْتُمُوْهُ قُلْتُمْ مَّا یَكُوْنُ لَنَاۤ اَنْ نَّتَكَلَّمَ بِهٰذَا سُبْحٰنَكَ هٰذَا بُهْتَانٌ عَظِیْمٌ ۟

Wa law laaa iz sami'tu moohu qultum maa yakoonu lanaaa an natakallama bihaazaa Subhaanaka haaza buhtaanun 'azeem

“And why did ye not, when ye heard it, say? - "It is not right of us to speak of this: Glory to Allah! this is a most serious slander!"”

Quran 24:16 (Yusuf Ali Translation)