Sahih al-Bukhari 4963
Sahih al-Bukhari · Book 65: Prophetic Commentary on the Qur'an (Tafseer of the Prophet (pbuh)) · "And whosoever does evil equal to the weight of an atom (or a small ant), shall see it." (V.99:8)
Narrated Abu Huraira:
حَدَّثَنَا يَحْيَى بْنُ سُلَيْمَانَ ، قَالَ حَدَّثَنِي ابْنُ وَهْبٍ ، قَالَ أَخْبَرَنِي مَالِكٌ ، عَنْ زَيْدِ بْنِ أَسْلَمَ ، عَنْ أَبِي صَالِحٍ السَّمَّانِ ، عَنْ أَبِي هُرَيْرَةَ ، رضى الله عنه سُئِلَ النَّبِيُّ صلى الله عليه وسلم عَنِ الْحُمُرِ فَقَالَ " لَمْ يُنْزَلْ عَلَىَّ فِيهَا شَىْءٌ إِلاَّ هَذِهِ الآيَةُ الْجَامِعَةُ الْفَاذَّةُ {فَمَنْ يَعْمَلْ مِثْقَالَ ذَرَّةٍ خَيْرًا يَرَهُ * وَمَنْ يَعْمَلْ مِثْقَالَ ذَرَّةٍ شَرًّا يَرَهُ} " .
The Prophet (ﷺ) was asked about donkeys and he replied, "Nothing has been revealed to me regarding donkeys except this comprehensive Verse which includes everything: "So whoever does good equal to the weight of an atom (or a smallest ant) shall see it; And whoever, does evil equal to the weight of an atom or a smallest ant) shall see it.' (99.7-8)