Musnad Ahmad 448:9

Ya'qub narrated to us, he said: My father narrated to us, from Ibn Ishaq, 'Ubayd Allah ibn Abi Ja'far al-Masri narrated to me, he said: Someone who heard Hanash al-San'ani narrated to me, saying: I heard Ruwayfi' ibn Thabit al-Ansari saying: I heard the Messenger of Allah, peace and blessings of Allah be upon him, saying: "Whoever believes in Allah and the Last Day, let him not sell gold for gold except weight for weight, and let him not have intercourse with a previously married woman from the captives until she has menstruated."