1 Corinthians 11:23-31

For I received of the Lord that which also I delivered unto you, how that the Lord Jesus in the night in which he was betrayed took bread; and when he had given thanks, he brake it, and said, This is my body, which is for you: this do in remembrance of me. In like manner also the cup, after supper, saying, This cup is the new covenant in my blood: this do, as oft as ye drink it, in remembrance of me. For as often as ye eat this bread, and drink the cup, ye proclaim the Lord's death till he come. Wherefore whosoever shall eat the bread or drink the cup of the Lord unworthily, shall be guilty of the body and the blood of the Lord. But let a man prove himself, and so let him eat of the bread, and drink of the cup. For he that eateth and drinketh, eateth and drinketh judgement unto himself, if he discern not the body. For this cause many among you are weak and sickly, and not a few sleep. But if we discerned ourselves, we should not be judged.