Musnad Ahmad 27:1352

'Affan narrated to us, Shu'bah narrated to us, he said: Jabalah informed me, he said: We were in Medina during the expedition of Iraq, and Ibn al-Zubayr used to provide us with dates. Ibn 'Umar would pass by us and say: "Do not practice *al-qiran* (combining two dates together when eating), for the Messenger of Allah (ﷺ) forbade *al-qiran*, unless a man among you asks his brother for permission."