﴿ وَلَوْلَآ إِذْ سَمِعْتُمُوهُ قُلْتُم مَّا يَكُونُ لَنَآ أَن نَّتَكَلَّمَ بِهَٰذَا سُبْحَٰنَكَ هَٰذَا بُهْتَٰنٌ عَظِيمٌۭ ﴾

“And [once again]: Why do you not say, whenever you hear such [a rumour], “It does not behove us to speak of this, O Thou who art limitless in Thy glory: this is an awesome calumny”?”

(Wherefore, when ye heard it) i.e. the slander of 'A'ishah and Safwan, (said ye not: It is not for us to speak of this) we are not permitted to speak about this lie. (Glory be to Thee (O Allah); This is awful calumny) this is a great lie.