Small chat with Shiite

Just now i talked to SHiite. He offered me a date to break my fast and i took it, but unfortuately my tongue doesnot obey me, and i said: May Allah be pleased with you.
Later when i came back i was told that the table is laid and meals are ready for those who broke fast. The SHiite was sitting opposite to me. 2 of us. When we started speaking of meat, he started first by saying that unless he witnesses himself that the animal is slaughtered with saying BISMILLAH he doesnt eat it. I offered him a chicken of mine, which i didnt intend to eat, that is how i triggered his speech.
My mistake was that i told him that i dont eat meat either, unless i witness how it is slaughtered. I could add that the important part of sharia compliant slaughter is that the person carrying out slaughter must be a muslim, stating at the same time, that the same person should not be the one worshipping graves, saints, praying to Allah only.
But instead of this i just said that it be Muslim who slaughters, without clarification whom i mean by saying Muslim.