Hadith No. 1184

Volume 2, Book 24, Number 525:
Narrated Um 'Atiyya (radiallaahu `anhaa):
A sheep was sent to me (Nusaiba Al-Ansariya) (in charity) and I sent some of it to 'Aisha (radiallaahu `anhaa). The Prophet (sallallaahu `alayhi wasallam) asked 'Aisha (radiallaahu `anhaa) for something to eat. 'Aisha (radiallaahu `anhaareplied that there was nothing except what Nusaiba Al-Ansariya (radiallaahu `anhaa) had sent of that sheep. The Prophet (sallallaahu `alayhi wasallam) said to her, "Bring it as it has reached its place."
What Nusaiba (radiallaahu `anhaa) had received was charity. She sent some of it to `Aisha (radiallaahu `anhaa) as gift. Prophet (sallallaahu `alayhi wasallam) agreed to eat it despite the fact that he could not accept charity for himself. Gifts, yes; charity, no. He said "Bring it as it has reached its place", meaning the person who had to give charity had done so. But when Nusaiba (radiallaahu `anhaa) sent it to `Aisha (radiallaahu `anhaa), it changed the status of that sheep from charity to gift. So it was accepted by the Prophet (sallallaahu `alayhi wasallam).

Taken from: http://ilookilisten.wordpress.com/2012/11/22/hadith-no-1184/