Bulugh al-Maram #690

‘Uthman Ibn ‘Affan (RAA) narrated, ‘Whenever the Messenger of Allah (ﷺ) finished the burial of the dead, he would stand by the grave and say, “Seek forgiveness for your brother and pray for him to be steadfast, because he is now being questioned.” Related by Abu Dawud. Al-Hakim graded it as Sahih.