Sahih Bukhari | Volume 3 | Hadith Number 670
Narrated 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."