Musnad Ahmad 1279:3

Ya'qub ibn Ibrahim narrated to us, my father narrated to us, from Ibn Ishaq, who said: Al-Zuhri narrated to me, from Ubayd Allah ibn Abd Allah ibn Utbah, from his father, who said: I wrote to Abd Allah ibn al-Arqam, ordering him to enter upon Subay'ah al-Aslamiyyah and ask her about her affair. He said: So he entered upon her, and he mentioned the hadith.