Al-Qasim ibn Muhammad reported: Aisha, mother of the believers, may Allah be pleased with her, fasted on the day of ‘Arafat as a pilgrim. Al-Qasim said, “I saw her in the evening on they day of Arafat as the Imam was departing. She stood until one could see the ground between her and the people, then she called for a drink and broke her fast.”
Source: al-Muwaṭṭa’ 819
Qatadah said, “There is no harm in fasting at ‘Arafat if one is not too weakened to supplicate.”
Source: Sharḥ al-Zurqānī 2/480
عَنِ الْقَاسِمِ بْنِ مُحَمَّدٍ أَنَّ عَائِشَةَ أُمَّ الْمُؤْمِنِينَ رضي الله عنها كَانَتْ تَصُومُ يَوْمَ عَرَفَةَ يعنى وَهِيَ حَاجَّةٌ قَالَ الْقَاسِمُ وَلَقَدْ رَأَيْتُهَا عَشِيَّةَ عَرَفَةَ يَدْفَعُ الْإِمَامُ ثُمَّ تَقِفُ حَتَّى يَبْيَضَّ مَا بَيْنَهَا وَبَيْنَ النَّاسِ مِنْ الْأَرْضِ ثُمَّ تَدْعُو بِشَرَابٍ فَتُفْطِرُ
819 موطأ مالك كتاب الحج باب صيام يوم عرفة
قَالَ قَتَادَةُ لَا بَأْسَ بِهِ إِذَا لَمْ يُضْعِفْ عَنِ الدُّعَاءِ
2/480 شرح الزرقاني على موطأ الإمام مالك