Several times during Christ’s ministry we see Him rebuking the Scribes and Pharisees for harshly judging others according to their traditions and not the doctrines of the Law of Moses.
In Matthew 15, Jesus does this when the Jewish elders judge Him for not ritually washing His hands. Ritual hand-washing is not part of the Law of Moses, but a tradition.
“Corban” or corbona denotes a gift, in this case, a gift to God or to the temple treasury. Instead of supporting their parents, as is required in the Law of Moses, Scribes and Pharisees would declare everything in their possession of value to be God’s or the temple’s. Therefore, they couldn’t possibly give any of it to their parents. Of course, it was possible to change one’s mind about one’s possessions.
Jesus is bringing the Jewish leaders’ hypocrisy to the forefront. They condemn Him for not indulging the tradition of ritual hand-washing, yet they twist the Law of Moses to cheat their own parents.