Sunan Abi Dawud, Hadith 1802

Hafsah, wife of the Prophet said Apostle of Allaah, how is it that the people have put off their ihram and you did not put off your ihram after your ‘Umrah. He said I have matted my hair and garlanded my sacrificial animal, so I shall not put off my ihram till I sacrifice my sacrificial animals.

حَدَّثَنَا الْقَعْنَبِيُّ، عَنْ مَالِكٍ، عَنْ نَافِعٍ، عَنْ عَبْدِ اللَّهِ بْنِ عُمَرَ، عَنْ حَفْصَةَ، زَوْجِ النَّبِيِّ صلى الله عليه وسلم أَنَّهَا قَالَتْ يَا رَسُولَ اللَّهِ مَا شَأْنُ النَّاسِ قَدْ حَلُّوا وَلَمْ تَحْلِلْ أَنْتَ مِنْ عُمْرَتِكَ فَقَالَ ‏ "‏ إِنِّي لَبَّدْتُ رَأْسِي وَقَلَّدْتُ هَدْيِي فَلاَ أَحِلُّ حَتَّى أَنْحَرَ الْهَدْىَ ‏" ‏ ‏.‏

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also referenced under: Hadith 1806 (DarusSalam)