a “But you say, ‘Whoever shall say to his father or his mother, ‘That by which you might have benefited from me is given to God', he need not honour his father.”
He points to one ruling whereby a man could withhold his wealth from helping his father and mother. By dedicating his wealth to the Temple in terms of an oath (without actually having to give anything, and ensuring that the oath would at some time terminate) he could point out that he could no longer give it away to them because it was the Temple's. For the rule was that while he could use for himself what was kept under oath, he could not give it away. However, Jesus said, the use of the Temple in this way was to make a mockery of God's commandment. They were using faithfulness to the very God Who had commanded them to honour father and mother as a reason why they should not do so, and that not honestly, but as a result of deviousness. This is, of course, a simplification of the situation, but as there was no comeback it would seem that they could not deny the truth of what He was saying. Thus clearly some such behaviour was well known. The Rabbis would indeed later legislate so that this excuse could no longer be used, possibly recognising the truth in what Jesus had said.