Abu Ayyub Ansaari Radiyallahu'Anhu reports:
"We were once present in the assembly of Rasulullah Sallallahu 'Alayhi Wasallam. Food was brought to him. 1 did not observe any food that had so much barakah at the beginning and at the end of which there was no barakah left in the food. We therefore asked Rasulullah Sallallahu 'Alayhi Wasallam reason?. He replied: 'In the beginning we all recited 'Bismillah' before we began eating. Then someone in the end joined us, and did not recite ''Bismillah'. The shaitaan ate with him'".
English reference: Book 27, Hadith 179
Arabic reference: Book 28, Hadith 188