Qays bin Abi Hazim narrates from the Prophet (peace and blessings be upon him) that he (peace and blessings be upon him) saw a fine high-humped she-camel among the zakah camels and asked the collector about it. He said: "I took it in exchange for (other) camels." So he (peace and blessings be upon him) remained silent.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الزكاة / 7375