Bulugh al-Maram, Book 3, Hadith 585 (English)

‘Abdur Rahman bin Abi Laila (RAA) and ‘Zaid bin Arqam (RAA) used to recite four Takbirat when praying over the dead, but once he said it five times, so I asked him about it. He said to me, ‘The Messenger of Allah used to do so.’ Related by Muslim and the four Imams.

وَعَنْ عَبْدِ اَلرَّحْمَنِ بْنِ أَبِي لَيْلَى قَالَ: { كَانَ زَيْدُ بْنُ أَرْقَمَ يُكَبِّرُ عَلَى جَنَائِزِنَا أَرْبَعًا, وَإِنَّهُ كَبَّرَ عَلَى جَنَازَةٍ خَمْسًا, فَسَأَلْتُهُ فَقَالَ: كَانَ رَسُولُ اَللَّهِ ‏- صلى الله عليه وسلم ‏-يُكَبِّرُهَا } رَوَاهُ مُسْلِمٌ وَالْأَرْبَعَةُ 1‏.‏ ‏1 ‏- صحيح.‏ رواه مسلم (957)‏، وأبو داود (3197)‏، والنسائي (4/72)‏، والترمذي (1023)‏، وابن ماجه (1505)‏.‏

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also referenced under: Book 3, Hadith 29 (In-Book)