Narrated `Abdullah bin `Abbas
That he heard As-Sa'b bin Jath-thama Al-Laithi, who was one of the companions of the Prophet, saying that he gave the meat of an onager to Allah's Messenger (ﷺ) while he was at a place called Al-Abwa' or Waddan, and was in a state of Ihram. The Prophet (ﷺ) did not accept it. When the Prophet (ﷺ) saw the signs of sorrow on As-Sa'b's face because of not accepting his present, he said (to him), "We are not returning your present, but we are in the state of Ihram." (See Hadith No. 747)
Narrated Abu Humaid Al-Sa`idi
The Prophet (ﷺ) appointed a man from the tribe of Al-Azd, called Ibn 'Utbiyya for collecting the Zakat. When he returned he said, "This (i.e. the Zakat) is for you and this has been given to my as a present." The Prophet (ﷺ) said, "Why hadn't he stayed in his father's or mother's house to see whether he would be given presents or not? By Him in Whose Hands my life is, whoever takes something from the resources of the Zakat (unlawfully) will be carrying it on his neck on the Day of Resurrection; if it be a camel, it will be grunting; if a cow, it will be mooing; and if a sheep, it will be bleating." The Prophet then raised his hands till we saw the whiteness of his armpits, and he said thrice, "O Allah! Haven't I conveyed Your Message (to them)?"