The Messenger of Allah ﷺ was asked about donkeys, and he replied, "Allah has not revealed to me anything concerning them except this unique and comprehensive verse, 'So whoever does an atom's weight of good will see it, and whoever does an atom's weight of evil will see it.'" [Zalzalah 99:7–8]
أن رسول الله ﷺ سئل عن الحمر، قال: ما أنزل الله علي فيها إلا هذه الآية الفاذة الجامعة: {فمن يعمل مثقال ذرة خيرا يره ومن يعمل مثقال ذرة شرا يره}
Bukhari reported it in the Tafsir (4962) and Muslim in the Zakat (987), both through the route of Zayd bin Aslam, that Abu Salih Zakwan Samman told him that he heard Abu Hurairah say it, mentioning it within a long account. It has also been reported that Abdullah bin Masud said, "This is the most decisive verse in the Quran."