Sa'id bin Jubayr said concerning this verse: "Why did they not bring to it" — meaning to the accusation — "four witnesses? And since they did not bring the witnesses, it is they who are the liars in the sight of Allah" [Surah An-Nur: 13], meaning those who accused Sayyidah Aishah.
Hadith Referenceالمعجم الكبير للطبراني / مسند النساء / 19495