Sayyiduna Wa'il bin Hujr (may Allah be pleased with him) narrates from the Prophet (peace and blessings be upon him) that he (peace and blessings be upon him) sent (a collector) to a man, and the man sent an emaciated young camel. The Messenger of Allah (peace and blessings be upon him) said: "The collector of Allah and of His Messenger came to him, and he sent an emaciated young camel. 'Allahumma la tubarik fihi wa la fi ibilihi' (O Allah, do not bless him nor his camels)." This reached the man, and he sent a beautiful, handsome she-camel. Then he (peace and blessings be upon him) said: "What the Messenger of Allah (peace and blessings be upon him) said reached so-and-so, and he sent his beautiful she-camel. 'Allahumma barik fihi wa fi ibilihi' (O Allah, bless him and his camels)."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الزكاة / 7658