Language:
كتاب الأيمان والنذور
83
Oaths and Vows
(15)
Chapter: If someone does something against his oath due to forgetfulness
(15)
بَابُ إِذَا حَنِثَ نَاسِيًا فِي الأَيْمَانِ
وَقَوْلِ اللَّهِ تَعَالَى: {وَلَيْسَ عَلَيْكُمْ جُنَاحٌ فِيمَا أَخْطَأْتُمْ بِهِ}.
وَقَالَ: {لاَ تُؤَاخِذْنِي بِمَا نَسِيتُ}.
Sahih al-Bukhari 6668

Narrated `Aisha:

When the pagans were defeated during the (first stage) of the battle of Uhud, Satan shouted, "O Allah's slaves! Beware of what is behind you!" So the front files of the Muslims attacked their own back files. Hudhaifa bin Al-Yaman looked and on seeing his father he shouted: "My father! My father!" By Allah! The people did not stop till they killed his father. Hudhaifa then said, "May Allah forgive you." `Urwa (the sub-narrator) added, "Hudhaifa continued asking Allah forgiveness for the killers of his father till he met Allah (till he died).

حَدَّثَنَا فَرْوَةُ بْنُ أَبِي الْمَغْرَاءِ، حَدَّثَنَا عَلِيُّ بْنُ مُسْهِرٍ، عَنْ هِشَامِ بْنِ عُرْوَةَ، عَنْ أَبِيهِ، عَنْ عَائِشَةَ ـ رضى الله عنها ـ قَالَتْ هُزِمَ الْمُشْرِكُونَ يَوْمَ أُحُدٍ هَزِيمَةً تُعْرَفُ فِيهِمْ، فَصَرَخَ إِبْلِيسُ أَىْ عِبَادَ اللَّهِ أُخْرَاكُمْ، فَرَجَعَتْ أُولاَهُمْ فَاجْتَلَدَتْ هِيَ وَأُخْرَاهُمْ، فَنَظَرَ حُذَيْفَةُ بْنُ الْيَمَانِ فَإِذَا هُوَ بِأَبِيهِ فَقَالَ أَبِي أَبِي‏.‏ قَالَتْ فَوَاللَّهِ مَا انْحَجَزُوا حَتَّى قَتَلُوهُ، فَقَالَ حُذَيْفَةُ غَفَرَ اللَّهُ لَكُمْ‏.‏ قَالَ عُرْوَةُ فَوَاللَّهِ مَا زَالَتْ فِي حُذَيْفَةَ مِنْهَا بَقِيَّةٌ حَتَّى لَقِيَ اللَّهَ‏.‏
Reference : Sahih al-Bukhari 6668
In-book reference : Book 83, Hadith 46
USC-MSA web (English) reference : Vol. 8, Book 78, Hadith 661
  (deprecated numbering scheme)