Bulugh al-Maram, Book 3, Hadith 20 (In-Book)

Asma’ bint ’Umais (RAA) narrated that Fatimah (RAA) (the daughter of the prophet made a will that ‘Ali (RAA) was to wash her when she dies.’ Related by Ad-Daraqutni.

وَعَنْ أَسْمَاءَ بِنْتِ عُمَيْسٍ رَضِيَ اَللَّهُ عَنْهَا: { أَنَّ فَاطِمَةَ عَلَيْهَا اَلسَّلَامُ أَوْصَتْ أَنْ يُغَسِّلَهَا عَلِيٌّ رَضِيَ اَللَّهُ تَعَالَى عَنْهُ } رَوَاهُ اَلدَّارَقُطْنِيُّ 1‏.‏ ‏1 ‏- حسن.‏ رواه الدارقطني (2/79/12)‏.‏

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also referenced under: Book 3, Hadith 576 (English)