Sahih al-Bukhari 6663
Sahih al-Bukhari · Book 83: Oaths and Vows · "Allah will not call you to account for that which is unintentional in your oaths ..."
Narrated `Aisha:
حَدَّثَنِي مُحَمَّدُ بْنُ الْمُثَنَّى ، حَدَّثَنَا يَحْيَى ، عَنْ هِشَامٍ ، قَالَ أَخْبَرَنِي أَبِي ، عَنْ عَائِشَةَ ـ رضى الله عنها {لاَ يُؤَاخِذُكُمُ اللَّهُ بِاللَّغْوِ} قَالَ قَالَتْ أُنْزِلَتْ فِي قَوْلِهِ لاَ، وَاللَّهِ بَلَى وَاللَّهِ.
regarding: 'Allah will not call you to account for that which is unintentional in your oaths...' (2.225) This Verse was revealed concerning such oath formulas as: 'No, by Allah!' and 'Yes, by Allah!' something against his oath due to forgetfulness should he make expiation?). And the Statement of Allah: 'And there is no blame on you if you make a mistake therein.' (33.5) And Allah said:-- '(Moses said to Khadir): Call me not to account for what I forgot.' (18.73)