Sahih Bukhari Volume 3, Book 44, Hadith Number 670.

Narated By Jabala : “While at Medina we were struck with famine. Ibn Az-Zubair used to provide us with dates as our food. Ibn ‘Umar used to pass by us and say, “Don’t eat two dates together at a time as the Prophet has forbidden eating two dates together at a time (in a gathering) unless one takes the permission of one’s companion brother.”