Sa'd, the freed slave of Sayyiduna Abu Bakr (may Allah be pleased with him), said: I placed dates before the Messenger of Allah (peace and blessings be upon him). The people were eating in front of him (peace and blessings be upon him) and eating them two at a time together, so the Messenger of Allah (peace and blessings be upon him) forbade qiran (eating two dates together).
Hadith Referenceالمعجم الكبير للطبراني / باب السين / 5477