Matt. 26:26-30—And as they were eating, Jesus took bread and blessed it, and He broke it and gave it to the disciples and said, Take, eat; this is My body. And He took a cup and gave thanks, and He gave it to them, saying, Drink of it, all of you, for this is My blood of the covenant, which is being poured out for many for forgiveness of sins. But I say to you, I shall by no means drink of this product of the vine from now on until that day when I drink it new with you in the kingdom of My Father. And after singing a hymn, they went out to the Mount of Olives.
For further reading please refer to CWWL, 1964, vol. 3, “Basic Principles for the Church Meetings,” ch. 5, pp. 28-29, 31.