Rejection of slander and false accusations

وَلَوْلَآ إِذْ سَمِعْتُمُوهُ قُلْتُم مَّا يَكُونُ لَنَآ أَن نَّتَكَلَّمَ بِهَـٰذَا سُبْحَـٰنَكَ هَـٰذَا بُهْتَـٰنٌ عَظِيمٌ

And why, when you heard it, did you not say, "It is not for us to speak of this. Exalted are You, [O Allāh]; this is a great slander"?