Musannaf Ibn Abi Shayba 13:929

Abu Bakr narrated to us, he said: Abd al-Wahhab narrated to us, from Ayyub, from Muhammad, regarding a man who buys a slave girl and she has an ailment, and he has intercourse with her before he discovers that: He said: It is more beloved to me that a portion of the price be deducted from him in accordance with that, and it is permissible for him.