Majma al-Zawaid 11204 — The tafsir of the story of the slander

Sa'id bin Jubayr said: (Allah Almighty says:) "When you were spreading it with your tongues." This refers to the time when the matter concerning Sayyidah Aishah (may Allah be pleased with her) had spread, and someone would say: I heard so-and-so mention such-and-such. So Allah Almighty said: "When you were spreading it with your tongues." This means: you were relating it to one another, saying, I heard it from so-and-so, and I heard it from so-and-so, "and you were saying with your mouths", that is, you were saying it with your tongues, meaning the one who accused Sayyidah Aishah (may Allah be pleased with her), "that of which you had no knowledge." This means: you did not know whether the accusation you were making was true. "And you were thinking it a light matter." This means: you thought that making a false accusation was a minor sin, "while in the sight of Allah Almighty it is great", that is, making a false accusation.
Al-Tabarani recorded it; its chain contains Ibn Lahi'ah, in whom there is weakness.
Al-Tabarani also recorded it in abridged form from Mujahid, and its narrators are thiqat (trustworthy).