This excerpt is taken from Sheikh Abu Hamza Abdul Khaliq Siddiqi's book Sahi Fazail-e-Amaal.
Eating together brings the benefit of the descent of blessings from Allah, the Exalted. As Sayyiduna Abu Hurairah (may Allah be pleased with him) narrates that the Messenger of Allah (peace and blessings be upon him) said:
طعام الإثنين كافي الثلاثة ، وطعام الثلاثة كافي الأربعة
"The food of two suffices for three, and the food of three suffices for four."
Reference: Sahih al-Bukhari, Book of Foods, Chapter: One person's food suffices for two, Hadith No: 5392 – Sahih Muslim, Book of Drinks, Chapter: The virtue of sharing in little food, Hadith No: 2058.
Similarly, in another blessed hadith it is stated that:
The food of one person suffices for two, the food of two suffices for four, and the food of four suffices for eight.
Reference: Sahih Muslim, also, Hadith No: 2059.