Al-Sa'b b. Jaththama al-Laithi reported that he presented a wild ass to Allah's Messenger (ﷺ) when he was at al-Abwa', or Waddan, and he refused to accept it. He (the narrator) said: When the Messenger of Allah (ﷺ) looked into my face (which had the mark of dejection as my present had been rejected by him) he (in order to console me) said: We have refused it only because we are in a state of Ihram.
Source: sunnah.com
Other translations
Arabic
حَدَّثَنَا يَحْيَى بْنُ يَحْيَى، قَالَ قَرَأْتُ عَلَى مَالِكٍ عَنِ ابْنِ شِهَابٍ، عَنْ عُبَيْدِ اللَّهِ بْنِ، عَبْدِ اللَّهِ عَنِ ابْنِ عَبَّاسٍ، عَنِ الصَّعْبِ بْنِ جَثَّامَةَ اللَّيْثِيِّ، أَنَّهُ أَهْدَى لِرَسُولِ اللَّهِ صلى الله عليه وسلم حِمَارًا وَحْشِيًّا وَهُوَ بِالأَبْوَاءِ - أَوْ بِوَدَّانَ - فَرَدَّهُ عَلَيْهِ رَسُولُ اللَّهِ صلى الله عليه وسلم قَالَ فَلَمَّا أَنْ رَأَى رَسُولُ اللَّهِ صلى الله عليه وسلم مَا فِي وَجْهِي قَالَ " إِنَّا لَمْ نَرُدَّهُ عَلَيْكَ إِلاَّ أَنَّا حُرُمٌ " .
sunnah.com