Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) said: "And had it not been for the favour of Allah upon you and His mercy" [Surah An-Nur: 20], meaning had Allah not shown you kindness and had mercy on your remorse — meaning (the remorse) of Mistah, Hamnah and Hassan — "and that Allah is Most Kind", meaning out of mercy, merciful towards you since you felt remorse and returned to the truth.
Hadith Referenceالمعجم الكبير للطبراني / مسند النساء / 19520
Sa'id bin Jubayr said: "Had it not been for the favour of Allah upon you and His mercy" [Surah al-Nur: 20]: that is, He would have punished you for what was said about Sayyidah Aishah. "And that Allah is Most Kind": that is, Most Kind to you, since He pardoned you and did not punish you for the words of slander.
Hadith Referenceالمعجم الكبير للطبراني / مسند النساء / 19521