In Matthew 16:8-12 Jesus was trying to show them, who is the source of their provision, by mentioning to them the two occasions, when he provided food for thousands of people, by a miracle.
The reason Jesus mentioned those to occasions of feeding the thousands supernaturally, was to show them, that when they do not have bread or need something, the source is not themselves, or their circumstances, but him.
That is why Jesus also mentioned to them, and asked them, how many baskets with left overs they had, on the two occasions. He wanted to show them, that he is the God of overflow, the overflow of provision.
Jesus did not only provide the thousands with food, but gave them more than they need, twice.
And that is the reason why he called them ¨You of little faith¨. The have seen twice the baskets with left over food, supplied by a miracle, and that should have been enough, to make their faith grow. But instead, they still discussed among themselves that they do not have bread.
Jesus was saying to them ¨I am the source of your provision, and not what you have or do not have.¨
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