Sunan An-Nasa'i

It was narrated from wa'il bin Hujr that:the Prophet sent a collector and he came to a man who brought him a slim, recently-weaned camel. The Prophet said: ""We sent to Zakah collector of Allah and His Messenger, and so-and-so gave him a slim, recently-weaned camel. O Allah, do not bless him nor his camels!"" News of that reached the man, so he came with a beautiful she-camel and said: ""I repent to Allah and to His Prophet. "" The Prophet said: ""O Allah, bless him and his camels!"" (Daif)