Musannaf Ibn Abi Shaybah 23182 — A man asked to swear who declines

It is narrated from Mughirah and Ibn Shubrumah that Abdullah bought a slave for a woman. When he took him to the house, the slave came down with a fever. He came to return the slave and took the dispute to al-Sha'bi (may Allah have mercy on him). He (may Allah have mercy on him) said to Abdullah: Bring witnesses that he concealed the slave's defect from you. He said: I have no witnesses. Al-Sha'bi (may Allah have mercy on him) said to the other man: Swear that you did not sell the slave in a state of illness. The man said: I turn the oath back onto Abdullah. Al-Sha'bi (may Allah have mercy on him) ruled that the oath was upon him and said: Swear, or else the slave is binding upon you.