Mark 8:17

17 Aware of their discussion, Jesus asked them: “Why are you talking about having no bread? Do you still not see or understand? Are your hearts hardened?

Read Mark 8:17 Using Other Translations

And when Jesus knew it, he saith unto them,Why reason ye, because ye have no bread? perceive ye not yet, neither understand? have ye your heart yet hardened?
And Jesus, aware of this, said to them, "Why are you discussing the fact that you have no bread? Do you not yet perceive or understand? Are your hearts hardened?
Jesus knew what they were saying, so he said, “Why are you arguing about having no bread? Don’t you know or understand even yet? Are your hearts too hard to take it in?

What does Mark 8:17 mean?

John Gill's Exposition of the Bible
Mark 8:17

And when Jesus knew it
As he did immediately, by his omniscience; for as he knew the thoughts and reasonings of the Scribes and Pharisees, ( Matthew 9:4 ) , so he did those of his own disciples:

he saith unto them, why reason ye because ye have no bread?
or imagine that I have given you this caution on that account; or are distressed because this is your case, as if you should be reduced to great difficulties, by reason of your forgetfulness and negligence:

perceive ye not yet, neither understand?
the meaning of the parabolical expressions, which he had used them to; or his power in providing food for them, and supporting a great number of persons with very little food, of which they had some very late instances:

have ye your heart yet hardened?
as after the first miracle; see ( Mark 6:52 ) , for it might have been expected, that by a second miracle of the loaves, their understandings would have been more enlightened, and their faith increased, and that they would have relinquished their gross notions, their anxieties, doubts, and unbelief.

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