Hadith 946 - Bab 161 (Supplication for the Deceased after his Burial)
Chapter 7 (The Book of Visiting the Sick)

Abu `Amr (also called Abu `Abdullah and also Abu Laila) from `Uthman bin `Affan (May Allah be pleased with him) reported: After the burial of a dead man, the Prophet (Peace be upon him) would stand by the grave and say, "Ask Allah to forgive your brother and supplicate for him for steadfastness because he is being questioned (about his deeds) now."

[Abu Dawud].

"Othmàn Ibn "Affàn (das) a dit: «Le Prophète (bsdl), quand on avait fini d"enterrer le mort, se tenait debout devant sa tombe et disait: «Priez pour l"absolution de votre frère et demandez à Dieu d"affermir sa langue dans ses réponses aux Anges de la mort car il est en train d"être questionné».

Hadith 947 - Bab 161 (Supplication for the Deceased after his Burial)
Chapter 7 (The Book of Visiting the Sick)

'Amr bin Al-'as (May Allah be pleased with him) used to say: "When you have buried me, keep standing near my grave till (for the time it takes to) a camel is slaughtered and its meat is distributed, so that I may feel your nearness and know what to reply to the angels sent by my Rubb."

[Muslim].

"Amr Ibn Al "As (das) a dit: «Une fois que je serai mort, restez autour de ma tombe le temps qu"il faut pour sacrifier un chameau et pour distribuer sa viande (entre les pauvres) afin que vous m"aidiez ainsi à supporter ma solitude et afin que je sache quoi répondre aux questions des Messagers de mon Seigneur (les Anges de la mort)». (Rapporté par Moslem)