Where does Christ promise to nourish and refresh believers with his body and blood as surely as they eat this broken bread and drink this cup?

In the institution of the Lord's Supper: "The Lord Jesus on the night when he was betrayed took a loaf of bread, and when he had given thanks, he broke it and said, 'This is my body that is [broken]* for you. Do this in remembrance of me.' In the same way he took the cup also, after supper, saying, 'This cup is the new covenant in my blood, Do this, as often as you drink it, in remembrance of me.' For as often as you eat this bread and drink the cup, you proclaim the Lord's death until he comes."¹ This promise is repeated by Paul in these words: "The cup of blessing that we bless, is it not a sharing in the blood of Christ? The bread that we break, is it not a sharing in the body of Christ? Because there is one bread, we who are many are one body, for we all partake of the one bread."²

*The word “broken” does not appear in the NRSV text, but it was present in the original German of the Heidelberg Catechism.