مِشْكَاةُ الْمَصَابِيحِ
Mishkat al-Masabih 133
Faith
Confirmation of the Punishment in the Grave - Section 2
وَعَن عُثْمَان رَضِيَ اللَّهُ عَنْهُ قَالَ: كَانَ النَّبِيُّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ إِذَا فَرَغَ مِنْ دَفْنِ الْمَيِّتِ وَقَفَ عَلَيْهِ فَقَالَ: «اسْتَغْفِرُوا لِأَخِيكُمْ ثُمَّ سَلُوا لَهُ بِالتَّثْبِيتِ فَإِنَّهُ الْآنَ يُسْأَلُ» . رَوَاهُ أَبُو دَاوُد
He also said that when the Prophet (ﷺ) finished the burial of the dead he stood over it and said, “Ask forgiveness for your brother, then ask that he may be strengthened, for he is now being questioned." Abu Dawud transmitted it.
Mishkat al-Masabih, 133Isnād Hasan (Zubair `Aliza'i)صَحِيح (الألباني) إسنادہ حسن (زبیر علی زئی)