Muwatta Malik, Book 20, Hadith 809 (In-Book)

Yahya related to me from Malik from Hisham ibn Urwa from his father that A'isha, umm al-muminin, said, "I do not mind whether I pray in the Hijr or in the House." (i.e. praying in the Hijr is the same as praying in the House).

وَحَدَّثَنِي عَنْ مَالِكٍ، عَنْ هِشَامِ بْنِ عُرْوَةَ، عَنْ أَبِيهِ، أَنَّ عَائِشَةَ أُمَّ الْمُؤْمِنِينَ، قَالَتْ مَا أُبَالِي أَصَلَّيْتُ فِي الْحِجْرِ أَمْ فِي الْبَيْتِ ‏.‏

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also referenced under: Book 20, Hadith 106 (USC-MSA)