The Book of Pilgrimage (Kitab Al-Hajj)
Muslim :: Book 7 : Hadith 2701
Al-Sa'b b. Jaththama al-Laithi reported that he presented a wild ass to Allah's Messenger (may peace be upon him) when he was at al-Abwa', or Waddan, and he refused to accept it. He (the narrator) said: When the Messenger of Allah (may peace be upon him) 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.