Jami` at-Tirmidhi, Book 49, Hadith 4220 (In-Book)

Narrated Anas bin Malik: "When the funeral of Sa'd bin Mu'adh was carried, the hypocrites said: 'How light his funeral is.' And this was due to his judgment concerning Banu Quraizah. So this reached the Prophet, and he said: 'Indeed, the angels were carrying him.'"

حَدَّثَنَا عَبْدُ بْنُ حُمَيْدٍ، أَخْبَرَنَا عَبْدُ الرَّزَّاقِ، أَخْبَرَنَا مَعْمَرٌ، عَنْ قَتَادَةَ، عَنْ أَنَسِ بْنِ مَالِكٍ، قَالَ لَمَّا حُمِلَتْ جَنَازَةُ سَعْدِ بْنِ مُعَاذٍ قَالَ الْمُنَافِقُونَ مَا أَخَفَّ جَنَازَتَهُ ‏.‏ وَذَلِكَ لِحُكْمِهِ فِي بَنِي قُرَيْظَةَ فَبَلَغَ ذَلِكَ النَّبِيَّ صلى الله عليه وسلم فَقَالَ ‏ "‏ إِنَّ الْمَلاَئِكَةَ كَانَتْ تَحْمِلُهُ ‏" ‏ ‏.‏ قَالَ أَبُو عِيسَى هَذَا حَدِيثٌ حَسَنٌ صَحِيحٌ غَرِيبٌ ‏.‏

sunnah.com