Musnad Ahmad 25:860

Zakariya ibn ‘Adi narrated to us, ‘Ubayd Allah informed us, from ‘Abd al-Karim, from ‘Ikrimah, from Ibn ‘Abbas, who said: A man went out from Khaybar, and two men followed him, and another was following them, saying: "Go back, go back," until he turned them back. Then he caught up with the first one and said: "Indeed, these two are devils, and I did not cease [working] upon them until I turned them back. So when you come to the Messenger of Allah, convey my greeting to him, and inform him that we are here gathering our alms, and if it were suitable for him, we would have sent them to him." He said: When the man arrived in Medina, he informed the Prophet, may Allah bless him and grant him peace. At that, the Messenger of Allah, may Allah bless him and grant him peace, forbade being alone [in seclusion with a woman].