Authentic Supplication Number 202.

Allah the Exalted said: "O you who believe! Eat of the good things that we have provided for you, and be grateful to Allah, if it is He you worship. (221)"

The Messenger of Allah  said: O my son! Invoke the name of Allah [say: Bismillah], eat with your right hand, and eat of that which is on your side [of the platter being shared].

(221) Surat 'Al-Baqarah (#2) V. 172.

Agreed upon by Bukhari and Muslim, and Al-Albani included this hadeeth in The Authentic of Good Sayings as #143.