Musnad Abu Ya'la al-Mawsili 154:106

Zuhayr narrated to us, Muhammad ibn Fudayl narrated to us, al-Shaybani narrated to us, from Jabalah ibn Suhaym, from Ibn Umar, who said: The Messenger of Allah (may Allah bless him and grant him peace) forbade *al-qiran* (combining two dates or pieces of food while eating) until you ask permission from your companions.