Albert Barnes Commentary John 6:30

"They said therefore unto him, What then doest thou for a sign, that we may see, and believe thee? what workest thou?" — John 6:30 (ASV)

What sign do you show? On the word sign, compare (see Barnes on Isaiah 7:14).

What miracle do you work to prove that you are the Messiah? They had just seen the miracle of the loaves in the desert, which was sufficient to show that he was the Messiah, and it would seem from the preceding narrative that those who crossed the lake to see him supposed that he was the Christ.

It seems surprising that they should so soon ask for further evidence that he was sent from God. However, it is not improbable that this question was asked by other Jews, rulers of the synagogue, who happened to be present and who had not witnessed his miracles. Those men were continually asking for signs and proofs that he was the Messiah. See Matthew 12:38-39; Mark 8:11; Luke 9:29.

As Jesus claimed the right to teach them, and as it was manifest that he would teach them differently from what they supposed Moses to teach, it was natural to ask him by what authority he claimed the right to be heard.