If someone does something against his oath due to forgetfulness
حَدَّثَنَا الْحُمَيْدِيُّ، حَدَّثَنَا سُفْيَانُ، حَدَّثَنَا عَمْرُو بْنُ دِينَارٍ، أَخْبَرَنِي سَعِيدُ بْنُ جُبَيْرٍ، قَالَ قُلْتُ لاِبْنِ عَبَّاسٍ فَقَالَ حَدَّثَنَا أُبَىُّ بْنُ كَعْبٍ، أَنَّهُ سَمِعَ رَسُولَ اللَّهِ صلى الله عليه وسلم {لاَ تُؤَاخِذْنِي بِمَا نَسِيتُ وَلاَ تُرْهِقْنِي مِنْ أَمْرِي عُسْرًا} قَالَ " كَانَتِ الأُولَى مِنْ مُوسَى نِسْيَانًا ".
Narrated Ubai bin Ka'b: that he heard Allah's Messenger (ﷺ) saying, "(Moses) said, 'Call me not to account for what I forget and be not hard upon me for my affair (with you)' (18.73) the first excuse of Moses was his forgetfulness."