You without understanding !
Diverting God's Commandment - Honor your father and your mother.

Lord Jesus Christ spoke about the misunderstanding of the commandment of God and diverting others also towards worldly things (things which come out of the man defiles it) - For Moses said, Honor your father and your mother; and, He who curses father or mother, let him be put to death. But you say, If a man says to his father or mother, Whatever profit you might have received from me is Corban (that is, a gift to God), then you no longer let him do anything for his father or his mother, making the word of God of no effect through your tradition which you have handed down. And many such things you do. When He had called all the multitude to Himself, He said to them, Hear Me, everyone, and understand: There is nothing that enters a man from outside which can defile him; but the things which come out of him, those are the things that defile a man. If anyone has ears to hear, let him hear! -  Mark 7:10-16

When Jesus Christ spoke about Corban, Its seems we understand the Commandment of God - Honor your father and your mother, that your days may be long in the land that the Lord your God is giving you - Exodus 20:12

Then why the Disciples asked Christ to explain the meaning again?  When He had entered a house away from the crowd, His disciples asked Him concerning the parable. So He said to them, Are you thus without understanding also? Do you not perceive that whatever enters a man from outside cannot defile him, because it does not enter his heart but his stomach, and is eliminated, thus purifying all foods? And He said, What comes out of a man, that defiles a man.  For from within, out of the heart of men, proceed evil thoughts, adulteries, fornications, murders, thefts, covetousness, wickedness, deceit, lewdness, an evil eye, blasphemy, pride, foolishness. All these evil things come from within and defile a man -  Mark 7:17-23 

Because this Commandment of God was written to Love the Lord Jesus Christ - But woe to you Pharisees! For you tithe mint and rue and all manner of herbs, and pass by justice and the love of God. These you ought to have done, without leaving the others undone - Luke 11:42