Muwatta Malik, Book 20, Hadith 102 (USC-MSA)

Yahya related to me from Malik from Yahya ibn Said that he had heard that A'isha, the wife of the Prophet, may Allah bless him and grant him peace, used to say, "Only the House frees a person in ihram from ihram."

وَحَدَّثَنِي عَنْ مَالِكٍ، عَنْ يَحْيَى بْنِ سَعِيدٍ، أَنَّهُ بَلَغَهُ عَنْ عَائِشَةَ، زَوْجِ النَّبِيِّ صلى الله عليه وسلم أَنَّهَا كَانَتْ تَقُولُ الْمُحْرِمُ لاَ يُحِلُّهُ إِلاَّ الْبَيْتُ ‏.‏

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also referenced under: Book 20, Hadith 804 (In-Book)