Sahih Bukhari
Prophetic Commentary on the Quran (Tafseer of the Prophet (PBUH))
Volume: 006 / Book Number: 060 / Hadith Number: 487
Narrated Abu Huraira:
The Prophet 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)