John the Apostle
John 6:52ESV·traditional attribution

The Jews then disputed among themselves, saying, “How can this man give us his flesh to eat?”

John Calvin Reformed @genevareformer

52. The Jews therefore debated among themselves. He again mentions the Jews, not by way of honor, but to reproach them with their unbelief, because they do not receive the well known doctrine concerning eternal life, or, at least, do not inquire modestly into the subject, if it be still obscure and doubtful.

Matthew Henry Presbyterian @wholebiblehenry

Whether this conference was with the Capernaites, in whose synagogue Christ now was, or with those who came from the other side of the sea, is not certain nor material; however, it is an instance of Christ's condescension that he gave them leave to ask him questions, and did not resent the interruption as an affront, no, not from his common hearers, though not his immediate followers.

Commenting on John 6:28-59

John Gill Reformed Baptist @doctorgill

Whoso eateth my flesh, and drinketh my blood,.... Spiritually by faith, as explained in the preceding verse: hath eternal life; the principle of spiritual life, which is evidently implanted in him, as appears from his eating and drinking; and is a durable and lasting principle: grace is an incorruptible seed; every part of it is abiding and permanent; and it is itself the beginning, pledge...