In Jesus days, the leaders of the Jews had developed a tradition whereby a child could refuse to assist his parents. In the following pericope, Jesus addresses that tradition:
9And he [Jesus] said unto them [the Pharisees and scribes], Full well ye reject the commandment of God, that ye may keep your own tradition. 10For Moses said, Honour thy father and thy mother; and, Whoso curseth father or mother, let him die the death: 11But ye say, If a man shall say to his father or mother, It is Corban, that is to say, a gift, by whatsoever thou mightest be profited by me; he shall be free. 12And ye suffer him no more to do ought for his father or his mother; 13Making the word of God of none effect through your tradition, which ye have delivered: and many such like things do ye.
Let us see first the commandments that Jesus identifies:
Exodus 20:12 Honour thy father and thy mother: that thy days may be long upon the land which the LORD thy God giveth thee.
Deuteronomy 5:16 Honour thy father and thy mother, as the LORD thy God hath commanded thee; that thy days may be prolonged, and that it may go well with thee, in the land which the LORD thy God giveth thee.
Exodus 21:17 And he that curseth his father, or his mother, shall surely be put to death.
Deuteronomy 27:16 Cursed be he that setteth light by his father or his mother. And all the people shall say, Amen.
Jesus has identified both the positive and negative ordinances that are relevant. The first ordinance was: honor your parents, the second, if you dishonor your parents, capital punishment.
Nevertheless, despite these commandments, the Jews (meaning the leaders, the Pharisees and Scribes) sought to find exceptions.
Scripture states only that the way to meet the exception was to say "it is a gift," by which we understand that they meant a gift to God. Scripture does not specify how they justified such a tradition.
According to one person with whom I was recently discussing the matter, the justification was an appeal to:
Numbers 30:2 If a man vow a vow unto the LORD, or swear an oath to bind his soul with a bond; he shall not break his word, he shall do according to all that proceedeth out of his mouth.
In other words, the justification would be that Numbers 30:2 can be used to trump paternal requests by vowing to give the item to God, and consequently tying ones own hands from granting one's parents request. This is a rather ironic interpretation, when one considers the context of the verse.
Likewise, this same person suggested that Leviticus 27:28 might be used to justify the tradition:
Leviticus 27:28 Notwithstanding no devoted thing, that a man shall devote unto the LORD of all that he hath, both of man and beast, and of the field of his possession, shall be sold or redeemed: every devoted thing is most holy unto the LORD.
The point is that if you give it to God, it is God's, and consequently you cannot sell it or redeem it. How could you sell it if you had already given it to God? Well, one might give some fraction of the fruit of the land to God. For example, someone might swear an oath to God that if God will give him a son, he will give God a third of the wheat that his land produces. The result is that every year, at harvest time, he needs to give that wheat to God, and not sell it.
So, how might someone seek to set those two verses against the first five? The answer is this, when your parents come to you for help, you swear an oath to give the things to God, which then prevents you from giving them to your parents. See? Ah, but wouldn't that mean you had to give them to God? Oh, no. You see, you just give them to God conditionally, upon the condition that you live 200 years, or you promise to given them to God in 200 years. You see? Now, you never have to give up your stuff, either to God or your parents. Amazing, eh?
But, of course, such an interpretation of the latter two verses is plainly wrong, not only because it is so patently absurd (since the person has no real intent to fulfill his vow to God), but because it contradicts the commands to honor one's parents. In other words, the interpretation is clearly wrong because it sets Scripture against Scripture. God authorized men to swear to Him and to devote things to him, but not in order to violate His commandments. A man may not lawfully swear an oath to kill an innocent man, although the Jews sometimes tried this:
Acts 23:12 And when it was day, certain of the Jews banded together, and bound themselves under a curse, saying that they would neither eat nor drink till they had killed Paul.
Nor would God honor such an oath. Those who make such foolish oaths place themselves under inescapable shame. So also with those who make oaths to avoid honoring their parents, or to steal, or to commit adultery.
God cannot be set against himself, but men are fond of trying to find ways to do so. The "Corban" exception was one such example, and (as noted above) Jesus pointed out that the Jews did many things like that.
May God give us grace not to elevate the traditions of men to the level of the Word of God,