Musannaf Ibn Abi Shayba 13:1264

Abu Bakr narrated to us, he said: Marwan bin Mu'awiyah narrated to us, from Musa bin Ubaydah, he said: Ata, the freed slave of Umar bin Abdul Aziz, informed me, saying: I bought a she-camel from Bard, the freed slave of Sa'id bin al-Musayyib, for four dinars. He came seeking his right from me, so I said: "I have dirhams, I do not have dinars." He said: "Until I consult Sa'id bin al-Musayyib." So he consulted him, and Sa'id said to him: "Take from him dinars in actual currency; if he refuses, then leave him to his appointment with Allah."