Hadithcore
Mishkat al-Masabih, 3882

Ibn ‘Abbas said:

God’s Messenger was a servant under command who applied to us* only three things which he did not apply to the people in general. He ordered us to perform ablution fully, not to consume <i>sadaqa</i>, and not to make an ass cover a mare. * He means the members of the Prophet’s family. Tirmidhi and Nasa’i transmitted it.

وَعَنِ ابْنِ عَبَّاسٍ قَالَ: كَانَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ عَبْدًا مَأْمُورًا مَا اخْتَصَّنَا دُونَ النَّاسِ بِشَيْءٍ إِلَّا بِثَلَاثٍ: أَمَرَنَا أَنْ نُسْبِغَ الْوُضُوءَ وَأَنْ لَا نَأْكُلَ الصَّدَقَةَ وَأَنْ لَا نَنْزِيَ حمارا على فرس. رَوَاهُ التِّرْمِذِيّ وَالنَّسَائِيّ

References1 variant
In-Book Reference
Book 19, Hadith 94