Musannaf Ibn Abi Shayba 13:851

Abu Bakr narrated to us, he said: Waki’ narrated to us, he said: Zakariya narrated to us, from ‘Amir, regarding a man who bought a slave girl and she had vitiligo, and he had no witnesses. He said: The seller shall swear by Allah that he did not sell her while she had vitiligo.