Corban

Concise Bible Dictionary:

This is the Greek word, κορβᾶν, representing the Hebrew word qorban, “an offering,” and signifies anything brought near or devoted to God. The Jews allowed, and perhaps encouraged, sons to devote their property to God, and then refuse to assist their parents under the plea that their substance was “corban,” or devoted. The Lord blames the rulers for this as one of their traditions, by which they had made the word of God of none effect (Mark 7:1111But 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. (Mark 7:11)).

From Manners and Customs of the Bible:

Mark 7:1111But 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. (Mark 7:11). 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.
The corban was an offering of any kind consecrated to God. It was right to make such offerings because God had commanded them; but the Saviour charges the Pharisees with placing their traditions above the Divine commands. For instance, God ordained honor and obedience to parents; but the Pharisees, by their traditionary explanation and abuse of the law of corban, completely nullified the law of parental honor. Their traditions taught that whatever was corban, that is, a gift consecrated to God, could not be alienated for any other purpose; but in the application of this principle, which in itself is correct enough, they manifested a wonderful ingenuity of perversion. If, for instance, parents desired help, and the son should say “My property is corban,” it released him from all obligation to sustain his parents; nevertheless, strange to say, it did not bind him to consecrate his substance to sacred uses. He could use it for his own purposes, or give it to whom he pleased, except to those to whom he had said, “It is corban.” No wonder the Saviour charged the Pharisees with “making the word of God of none effect” through their tradition.