Bulugh al-Maram, Book 5, Hadith 708 (English)

'A’isha and lbn 'Umar (RAA) narrated, ‘Nobody was allowed to fast on the days of Tashriq except for those, who could not afford the Hadi (sacrifice).' Related by Al-Bukhari.

وَعَنْ عَائِشَةَ وَابْنِ عُمَرَ رَضِيَ اَللَّهُ عَنْهُمْ قَالَا: { لَمْ يُرَخَّصْ فِي أَيَّامِ اَلتَّشْرِيقِ أَنْ يُصَمْنَ إِلَّا لِمَنْ لَمْ يَجِدِ اَلْهَدْيَ } رَوَاهُ اَلْبُخَارِيُّ 1‏.‏ ‏1 ‏- صحيح.‏ رواه البخاري ( 4 / 242 / فتح )‏.‏

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also referenced under: Book 5, Hadith 688 (In-Book)