Muwatta Malik, Book 16, Hadith 46 (USC-MSA)

Yahya related to me from Malik from Hisham ibn Urwa from Abbad ibn Abdullah ibn az-Zubayr that A'isha, the wife of the Prophet, may Allah bless him and grant him peace, told him that she had heard the Messenger of Allah, may Allah bless him and grant him peace, say before he died, while he was leaning on her breast and she was listening to him, "O Allah, forgive me and have mercy on me and join me with the highest company."

حَدَّثَنِي يَحْيَى، عَنْ مَالِكٍ، عَنْ هِشَامِ بْنِ عُرْوَةَ، عَنْ عَبَّادِ بْنِ عَبْدِ اللَّهِ بْنِ الزُّبَيْرِ، أَنَّ عَائِشَةَ، زَوْجَ النَّبِيِّ صلى الله عليه وسلم أَخْبَرَتْهُ أَنَّهَا سَمِعَتْ رَسُولَ اللَّهِ صلى الله عليه وسلم قَبْلَ أَنْ يَمُوتَ وَهُوَ مُسْتَنِدٌ إِلَى صَدْرِهَا وَأَصْغَتْ إِلَيْهِ يَقُولُ ‏ "‏ اللَّهُمَّ اغْفِرْ لِي وَارْحَمْنِي وَأَلْحِقْنِي بِالرَّفِيقِ الأَعْلَى ‏" ‏ ‏.‏

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also referenced under: Book 16, Hadith 568 (In-Book)