An onager was presented to Messenger of Allah ﷺ at the place called Al-Abwa' or Waddan, but Allah's Apostle rejected it. When the Prophet ﷺ noticed the signs of sorrow on the giver's face he said, "We have not rejected your gift, but we are in the state of Ihram." (i.e. if we were not in a state of Ihram we would have accepted your gift, Fath-ul-Bari page 130, Vol. 6)  

أَنَّهُ أَهْدَى لِرَسُولِ اللَّهِ ﷺ حِمَارًا وَحْشِيًّا وَهْوَ بِالأَبْوَاءِ أَوْ بِوَدَّانَ فَرَدَّ عَلَيْهِ فَلَمَّا رَأَى مَا فِي وَجْهِهِ قَالَ أَمَا إِنَّا لَمْ نَرُدَّهُ عَلَيْكَ إِلاَّ أَنَّا حُرُمٌ